There are some linux distros specifically for older/low-end hardware:

• https://www.q4os.org/
• http://tinycorelinux.net/
• https://www.damnsmalllinux.org/

Of that list I tried Q4OS on an EEE pc. It worked ok, but mainly modern websites are just way too heavy and unoptimized.

Install Debian with an LXDE or LXQT desktop manager.

The RAM limitation is really the deciding factor. You'll probably have trouble running Home Assistant, so that's out. You could probably get some sort of super light desktop running, but it'll still probably bail after a bit of use. Aside from very small tasks, I don't think it's going to be of much use.

If you could attach some storage to it, you could make it into a basic NAS. Note, no advanced apps running, just pure file sharing.

Photo frame?

Weather station (as in shows temp, barometer, humidity, forecast, etc).

Both?

Might be sensible as a mini home server for running small scripts.