Is the darts minigame in the Final Fantasy VII Remake based on a real variant of darts?
301 is a valid variation of darts.
Straight-out, where you can finish on anything (as long as you don't go below 0 score), is a valid variation too.
I have never known anyone to play 50 points for outer bull though.
Having said that, the beauty of darts is you can play any rules you want as long as all players agree.
To be specific though, I dont believe there is a commonly played variant (with a specific name) that meets all this criteria. Closest would be "301 straight-out".