I used KeePass2Android for a long time on devices without GOS but I don't think the project is actively worked on anymore.
I used KeePass2Android on other devices because of the built-in keyboard that does not spy on your password and the auto fill feature this keyboard has but that's no longer an issue with GOS. The app has some issues with GOS's enhanced security features so I do not mind ditching it.

What FOSS projects (and links to these projects) are currently suggested as offline database password manager for privacy and strong security and can I export my current KeePass2Android database and import them so I don't have to rebuild my kdbx database.

I don't need any online features. I want to stay in full control of my passwords. The database is used offline but offline integrated backup sync to USB features would be nice.

    there seems to be quite an amount of KeePass forks out there. I think as KeePassDX has been the mainstream-option for a long time, that's probably your best bet.
    Then there's the lesser known forks such as this or this, but I'd always be careful with these, since you don't know how experienced the developers are and if there are any inherent security flaws. If you have the experience with reading code (which I doubt), you really can't know. And we're talking about passwords after all.
    In my opinion, KeePassDX is what you should stick to. It's still in active development and matches all of your criteria, without being a piñata.

      splattergames thanks for the suggestion. I will have a look at the current state of KeePassDX (I can read code, for the most part). I always stuck with KeePass2Android out of familiarity (and some laziness on my part). Hopefully it's an easy import and export because that's the only thing holding me back. The kdbx files of K2A are still encrypted but the project seems dead so I have to move on.

        FOSSOS from what I've heard it's pretty easy to import a keepass db into DX. I personally use my own Vaultwarden instance and haven't touched KeePass in a long time, but at least a few years ago (2021ish) I had no trouble at all. Good luck!

          FOSSOS so I don't have to rebuild my kdbx database.

          KeePassDX, I guess

          splattergames vaultwarden would be the best solution but then I'll have to invest in running an instance again and I have all LAN blocked by default since I don't use it so it's a hassle to set it up.

          I will check KeePassDX's current state. Thanks!

            FOSSOS I will check KeePassDX's current state

            it's maintained, supports OTP, and as it's file-based, one can back it up to a trusted place, be it cloud or another device(s) via Syncthing

              FOSSOS that is the downside, but since I run my little server for quite a lot of services (Immich, Nextcloud, Vaultwarden, Syncthing, AdGuard Home and quite a few others), it's really worth it in the end. Having all ports blocked is a nice thing of course, but with some proper security measures it's not as catastrophic as people make it out to be.
              KeePassDX has had its last release in June and seems to be on its normal release cycle.

                mmobder to a trusted place, be it cloud or another device(s) via Syncthin

                Is the current KeePassDX github still https://github.com/Kunzisoft/KeePassDX ?
                Checking to make sure I add the most current project to my obtainium

                splattergames that is the downside, but since I run my little server for quite a lot of services (Immich, Nextcloud, Vaultwarden, Syncthing, AdGuard Home and quite a few others), it's really worth it in the end. Having all ports blocked is a nice thing of course, but with some proper security

                What are you using to run your server? I used to have a RAID NAS but the expenses outweighed the use. If I can run something similar on a RPI it will be much more interesting since I could run a unifiedpush, too.
                I've been out of the loop with LAN devices. I also drastically need to expand my router setup (r7800 with ddwrt) to include some form of WIFI 6E mesh or AP but I have been so out of the loop with this (my own fault) that I don't even know where to start. (Off-topic, my apologies mods)

                  FOSSOS I run it on a pretty busted Fujitsu office tower. It has an i5 7500, 32GB of RAM, 2x 2TB SSDs as my data drives (in RAID1) and a generic 250GB NVME SSD as my OS/boot drive. I run OMV on top of it. I haven't yet received another electricity bill since I spun that thing up, I hope it's not gonna be too extreme. I guess that is the price you have to pay to keep your data in control while also keeping the convenience.
                  Most of the stuff I mentioned will run totally fine (simultaneously) on the newest RasPi. And I think that will be a pretty good price/performance ratio. I'm only unsure about Immich, but that is not a must. I only really run that config because of OnlyOffice (basically a selfhosted Google Docs) which eats a whopping 9GB of RAM alone.

                  As on networking stuff, it's kinda the most annoying part. Options are very limited, OpenWRT is the way to go, mesh should be doable, I'm just the wrong person to ask this. My knowledge on that topic is fairly limited and I don't want to give incomplete or dangerous advice.

                  FOSSOS I've been using DX on mobile for years now and it's been mostly great. I use KeePassXC on the desktop, and keep everything synced with Syncthing. Like you, I'm not at all interested in server-based credential management.

                  The official Android version of Syncthing (Syncthing-android) was recently discontinued, however the maintainers are now suggesting Syncthing-fork as an alternative for mobile.