Hi there! Thank you for giving GrapheneOS a chance. Let me address your main points:
Google Maps can be used without Sandboxed Google Play, and without Play Services location. I know, because I use it that way. By default, it'll use GPS location, so if you were having trouble with getting a location lock initially, it might have been because you were inside. I'd recommend giving this a shot in a new profile without Sandboxed Google Play:
Install Google Maps and "GPSTest" from Aurora Store, make sure you have a SIM card in your phone and go outside for a few minutes with the phone having a clear view of the sky. GPSTest will show you if you're getting a location lock, at which point you'll know that your location should work. You can then give Google Maps a shot and see if it works out for you.
I know that can seem cumbersome, but that's why GrapheneOS provides you with the option to use Play Location if you want. That's not the default, even if you use Sandboxed Google Play, though.
No Simple Backup solution
I'm with you here; Seedvault is not great. The team is fully aware and on board with this. As someone above me mentioned, the plan is to replace the current backup solution with one that is more flexible and reliable, while still being secure, encrypted, and all that good stuff.
Namely, it will have proper SAF (Storage Access Framework) support, so that you can store your backups to any cloud provider you choose. That can be something you host yourself, or a service you pay for (Dropbox, for example). As long as the service can appear as an option in the File Manager, the new backup app will be able to use it.
I know these are a lot of "will" statements, so that doesn't help you right now, but we'll get there. :) For the time being, I would recommend making backups of individual apps that have app data you care about. Some apps like Signal will even automatically generate backups on a schedule.
Other small things which are more android specific and not graphene
- I'm with you on the design. I, too want all of my apps to have a beautiful, modern and uniform design. More and more modern apps are using the latest Material design guidelines, with Material You etc., you just have to be a bit more picky with which apps you choose. You mentioned that you use F-Droid as your source of apps, which is a repository which houses apps of all kinds, no matter how up to date or out of date they are. I'm not saying that the Play Store enforces these things, but generally the more up to date an app, the more likely it's UI is also updated.
- https://grapheneos.org/usage#carrier-functionality has some information on Visual Voicemail, if you haven't checked it out yet:
If you are having issues with Visual Voicemail, please be aware that AT&T USA users are unable to use this feature currently due to a lack of AOSP support. Other carriers are done on a best effort basis. We would suggest using Google Dialer with sandboxed Google Play if you are unable to get this feature working.
- I'm not sure I can help with emojis, haha. :)