Pretty hard. If you don't have prior experience with the AOSP codebase, I'd say it's impossible. But if you want to get started, this is how to build GrapheneOS from source: https://grapheneos.org/build
Andromxda
Ok that actually makes sense. I just realized that the fucking iPhone has this feature, but Android doesn't. GrapheneOS doesn't implement any custom features that aren't privacy/security related. And no, unfortunately you don't get a second VPN slot either.
As far as I can see, no. But what benefit would that really have? Network settings (including mobile networks) are global. The only thing that's profile-specific is your VPN setting. You can only disable a profile's ability to use the phone/SMS feature. Profiles generally manage apps, user data and some settings.
Ok that's reasonable
Google Fi is the one thing I have no experience with, as I'm not American. But all SIMs should work fine on Graphene, and eSIMs are supported through a compatibility layer, which enables Google's proprietary eSIM management tool (this is not the same as Sandboxed Google Play services, and you don't need Google Play for eSIMs). All the eSIMs and physical SIMs I tried work just fine. Google Fi seems to work, according to this thread on the Graphene Forum: https://discuss.grapheneos.org/d/7950-does-grapheneos-work-with-google-fi/6
Enjoy your spyware-free degoogled experience! Feel free to dm me if you have any questions. I'd say I'm quite experienced with GrapheneOS, degoogling and Android in general.
Both. Buy physical media, rip the audio files and put them on your selfhosted music server (e.g. Navidrome). Or pirate the music and buy some merch to compensate the artists.
No need for Telegram bots. There are both proprietary and open source apps that you can use to do this yourself. Check out https://rentry.org/firehawk52 and https://ripped.guide/Audio/Music/
Everybody ~~buy~~ pirate your music. These streaming platforms are trash.
I recommend Bazzite instead. It's based on Universal Blue (which is actually based on Fedora Atomic) and gives you a super easy and stable experience.
I'm waiting for some FOSS developers to hack this thing and run custom firmware on it. Or someone who creates their own "Car Thing" using an Arduino or Raspberry Pi.
There might be an easier way to accomplish this. The RethinkDNS app has a built-in Firewall and WireGuard VPN client. It also allows you to configure per-app Wifi and cellular data separately. The only caveat is that you would need to manually import the WireGuard profiles from your VPN provider.