Absolutely! Here’s how we do it:
Before each spin, we generate a random number (0..36) and a salt, then publish the SHA-256 hash of num:salt
After the spin, we reveal the salt, so you can re-hash the exact same num:salt combination.
If the hash matches what we published before the spin, you know the result couldn’t have been altered.
Then there is a problem with your provably fair engine because if you don't like the result you can select a new random number to mix it with that salt.
Let's say users are betting on 11, and your engine select a random number with the salt and the result of that gives 11, then you can try with another random number and get a number different than 11. The fact that you apply a random number to the provably fair engine is tricky because you can reroll that number until you get the desire result and then publish the sha-256.
For me, your engine isn't provably fair, sorry.