The 6810 is a Commodore Semiconductor Group (CSG) part, not a WDC part, and I don’t know if WDC even has the right to manufacture versions of it. (What happened to CSG’s IP after Commodore went bankrupt, anyway? Did GMT Microelectronics get it? They went out of business, too.)
Anyway, if they did, they would almost certainly be CMOS, so there would be some minor software incompatibilities. I can’t see why they would, though; the main difference is the 6 pins of digital I/O, and WDC has full-on 6502-based microcontroller units with lots of I/O for the market that wants that.
The W65C02 does have a bus enable signal that does the same thing as the 6501’s AEC, though, so that does solve one hardware compatibility problem. The only other thing you’d need would be a minimal PIA on addresses 0 and 1 (as I’d mentioned above). And then avoid software that requires the 6502’s bugs and illegal instructions.