I have a power mirror on the driver side but a manual on the passenger side.
So DUMB of Nissan, having the power window where driver could reach out to adjust, but manual mirror when driver might have to get out/adjust/get back in, check, etc. half a dozen times. That said: Mrs. Cusser had a 1982 Pontiac Firebird that was like that !!!
Can I just install a new power mirror?
My 1st generation 2004 Frontier has power mirrors on both sides (my 1998 is manual on both). I would guess if one was handy enough that mirrors and switches/parts from a 1st generation Frontier could be obtained from a parts yard and installed. You might want to pull both sides to make sure the mirrors match.
If you're asking whether there is a wiring harness for such hidden inside there, or if a right-side power mirror could simply be ordered: I don't know.
Now, my daughter has a 1998 Pathfinder, think that's power mirror or passenger side. So possibly that's an option too.