Confusing, do you have a Mavic Pro (M1P) or a Mavic 2 Pro (M2P) ?
And no the M3 controllers would not be compatible, but you should be able to find refurb RC1A (or other suitable) via various suppliers, or 2nd hand if needed via sites like ebay, facebook marketplace, etc.
Edit - the original mavic pro (and platinum pro) used the GL200A controller only.
the M2P/Z or enterprise models used the RC1A