Yes, I've been using it as my daily driver since it got updated to focal on my Oneplus 5T. It will depend on how good your device is supported though. You can even run most Android apps with Waydroid (Android container), but I rarely feel the need to use that.
Fascinating. I have been looking at setting up a Linux Phone for a while but given how well my LineageOS with microG phone works, I haven't made the leap. 90% of my apps are from F-Droid but there are still those apps like banking apps or rideshare which I need.
I think it is cool you are developing a Nostr client for Linux phones!