Multiplayer

I tried it a few months ago and people were still playing on PC, even if it takes a bit longer to get a team together.

Even Mass Effect 3 is still active on PC. Now consoles, that's another matter. Console players tend to move on to new games more quickly, but I don't have any Mass Effect games on a console, so I can't check.

On Xbox.

No issue at all getting a squad for ME3.

Andromeda I've not played for a while to be honest.

I played on Playstation and Xbox for a while and it was working. I'm now on PC and don't have any issues playing for finding a squad. Some times it take a short while to get a squad together but friends and I still actively play.