If you buy it from GOG you should be able to get the Windows exe, you can then try and install it with WINE. That should give you the game files to import into OpenRCT2.

There's innoextract for gog executables

Buying RTC Classic from Steam (which is available on macOS) is probably a better idea. It's an update to the game featuring both RCT1 and RCT2 campaigns.

RCT Classic is one way of getting the files but it's cheaper to buy RCT2 then load it in OpenRCT2. But to each their own as long as you're having fun.