It would work a Meshtastic repeater from the ISS?

It would not. We would need to make a case to add Meshtastic. Amateur radio has had a much better chance since the days of the Space Shuttle. Astronauts routinely make ISS to Earth contacts with amateur radio operators. There is also ARISS.

5w ISS contacts are hard enough as it is

LoRa is extremely robust and can work with super weak signals. At the price of being very very slow in the most reliable configuration .

That combination is toxic for a high amount of parallel users.

I think it would need big modifications: fast uplink and robust slow downlink.

APRS requires a license right?

Correct. Developed by the late Bob Bruninga. I had many email exchanges with Bob and we were able to send SSTV images through his NO-* series of amateur radio satellites with some technical advice a few years ago.

APRS is much more extensive and even available via commercial ham radio

That's kind of the benefit of LoRa though. Cheap unlicensed radio that works surprisingly well for what it is.