Update: I configured Vanadium to install apps, sent the necessary .apk files to a server, downloaded them through Vanadium and got them installed that way. A long detour, but at least they're in.

Did you at any point just single click the apk file? If you have an intact apk in any folder, you should be able to simply open it. Opening it through an app > files will require permission to install.

Going from the base files app just has a warning or two.

Graphenator
Open the Files app ->
Open the "Device directory",
the one labelled with the Device Model
( it serves as a root directory
for Shared External storage) ->
From there navigate to the folder where
you copied the APK ->
Try regular tap and install - this should work.

    Thanks for the feedback, everyone.

    No idea why, but today everything seems to be working as it did with the Pixel 4A: if I do what I did yesterday I get a prompt asking me if I want to upgrade the app. Single tap also seems to work. Weird ... but an academic question now, as I've got f-droid in and can continue with configuration.

      Graphenator Highly recommend you use Droid-ify over F-Droid. More modern, less vulnerability-- also comes pre-loaded with alternate repos.

      having originally installed Threema from threema shop, paid and got a licence, i have downloaded the latest apk after a recent update but I am not able to update the current version nor can I clean install the new apk, after uninstalling the previous version, I get the message "App not installed as package appears to be invalid" what did I do wrong.... thanks

        pistone It sounds like you have either another variant or a newer version of Threema installed (in any profile). Check all your profiles and make sure that's not the case, then try again.

        5 months later

        Note: As of now there is a small issue with the default file browser and installing .apk:
        In order to install an app from a .apk within the file manager you first need to navigate to your device directory on the top left menu (last option at the bottom). From there go to wherever your .apk is and now it will ask to install it when you tap the file.

          3 months later

          Xampa Could somebody explain the difference it makes if I install the apk via Files or via Firefox? Is there a difference security-wise?

            wojon

            For a file you just downloaded from Firefox? Then it shouldn't matter. Just make sure it's a trustworthy app from a trustworthy source and be careful about the permissions you grant to the app.

            a year later

            Xampa

            In order to install an app from a .apk within the file manager you first need to navigate to your device directory on the top left menu (last option at the bottom). From there go to wherever your .apk is and now it will ask to install it when you tap the file.

            Thanks for posting this workaround, as of May 2024 this is still needed so I'm wondering if it is now considered a 'feature' or if there is a fix in the pipeline.

            4 months later

            Just chiming in to say this is still an issue, I cannot simply click on an APK in the downloads folder.

              Clicking on an APK in the download folder works for me.

              thrik what happens if you try? It works for me, so maybe knowing what actually happens can help us help you figure out a fix.

                13 days later

                other8026

                Sorry for the delay. It usually pops up with the "Open with" and shows a few random apps to try to open the apk file with. Sorry that I did not grab a screenshot. However, what Xampa said above worked as a workaround.