So, after following the discussions for quite a while, I decided to pull it off.
Having gone though the support list of various distributions, I chose Pixel 3a for my setup. Among the dirt cheap smartphones, it seems to enjoy the support of almost everything.
I decided to install PostmarketOS with Plasma Mobile. In the meanwhile, I also tested Mobian (didn't work for me for some reason) and Gnome (I ended up being too much of a KDE fanboy).
The overall experience is, honestly, mixed. It sure is exciting, and I've spent a whole day tinkering here and there (and feeling a bit nostalgic for the day I felt this way about Linux as a whole), the hardware support was a pleasant surprise, up to multipoint Bluetooth TWS headphones, but still, system stability isn't anywhere near a daily driver, and software support lags behind in many ways.
In any case, now I too have a platform to look into the future. Year of Linux mobile, anyone? :)
P.S. Any advice on censorship-resistant (VLESS/Reality/AmneziaWG-based) VPNs for PostmarketOS on ARM devices?
For fun, privacy, or testing even if it's not ready for prime time?
Fair!
For me it's mostly just fun, and this little joy of having everything run Linux, lol
But also to see for myself the current state of things.