Recent best little projects for me was moving home assistant from raspberry pi to proxmox as a VM. A coupe of the challenging ones was setup frigate nvr in docker & getting the TPU to work with it. Then integrating it with home assistant over mqtt. I was driven to set this up to get to turn a cheap ip camera into a smart camera & stop all the false alerts & actually identify what it found. Then only send notifications only when conditions are met, like a person in my driveway or by my front door. Or simply record all dogs so that I can find out who’s repeatedly not picking up after their dog pooped on verge.
Another was to liberate my roborock s5 robot vacuum from the cloud by flashing valetudo. It really just throws a web server onto the vacuum to answer & trigger the API calls, so give local control & no longer needs their cloud or their app. It’s now also integrated with home assistant as well & can use the Siri voice commands as I leave the house.
I’ve played around with Ubuntu touch from ubports foundation on an old pixel 3a. It works ok as a basic daily driver. Depending on the phone model there’s support for waydroid which helps with using android apps.