Can a P226 slide be used on a P227 frame? Thanks

The 226 platform is used for three "short" overall length cartridges. 9mm, .40 S&W, and .357 Sig.
The 226 platform also has the "short" overall length magazine well and corresponding "short" length (front to back) double stack magazines.

The 227 platform is used for one "long" overall length cartridge. .45ACP and has a double stack width, "long" length magazine well.
The 220 platform is used for three "long" length cartridges, .38Super, 10mm, .45ACP and also has the "long" overall length magazine well and corresponding "long" length (front to back) magazines.
The 220 also is more rarely found in 9mm, and in other countries may be found chambered in more obscure non-traditional cartridges.

The 227 uses double stack magazines, and the 220 uses single stack magazines.

There just isn't much in common between the 226 design and the 227 design other than being double stack and looking similar. Even "IF" the 226 slide slid on the 227 frame rails. Don't know, never tried.

If you could locate suitable magazines, it would be technically possible to use .38Super in a 227. You would need a .38Super slide, barrel, recoil spring assembly and likely a locking block.

If SIG had made a 227 in all stainless (frame) then it's quite possible it could be built to fire 10mm. 227 frames are aluminum so 10mm is out in a 227.

If you have a 227, enjoy it. Then go buy a 226, maybe even a few!

If Bruce Gray happens to see this thread, he may be able to further address your question.