I have a Riello UPS. The UPS has an expansion slot for optional communication cards that allow the unit to communicate using the basic communication standards RS232 and USB port.
My question is: Is it possible to use (would it work?) an RS232 to Ethernet TCP/IP converter to communicate via NUT?
Does it require at least Raspberry?
There was someone on the forums with a project like that this year.
Do some searching. This might help.
Tips on Searching for Answers & Duplicate Topics in the Forum.
I took pi zero (w2), got myself proper usb cable (usb b to micro usb, you can get it on aliexpress). Then i installed basic raspbian (without desktop) on my pi zero, installed NUT according to THIS MANUAL and it works perfectly.
For easier setup you can get old classic Pi - it also allows ethernet connection, while with zero you’re stuck on wifi.