Asking an XTP hollow point bullet - or just about any hollow point, for that matter - to open up under 38 Special (+P implied throughout this post) pressures/velocities is a tall order. And that's with any barrel length - much less, snubbies.
With the exception of Speer Gold Dot Short Barrel bullets (110gn & 135gn), most other designs won't reliably expand until about 1100 fps or so - maybe a little less. Through a 2" bbl snubbie, the necessary velocities can only be achieved with the 110's - maybe.
The Speer GDHP SB's are hard to find. If you can find them (135's preferred), they would be the best way to go. However, with the current demand right now, they are all allocated for factory ammo. (Speaking of which, it wouldn't be a bad idea to consider just buying this factory product. But that wasn't the question of your post.) During this 30-month long component shortage, I've seen the 110's available for loading (and purchased them), but not the 135's.
Assuming you're interested in making self-defense ammo, and want to stay within SAAMI pressure standards (i.e. published data), maybe another approach is in order. . .
There's a lot of schools of thought on this subject. This post is just mine. There will be other opinions, no doubt. With short barreled guns, less energy is lost with heavy bullets, than light ones. So it follows to use a heavy bullet to deliver maximum energy. No, you won't get expansion. But you'll make a hole. And making a hole should be your first priority. If you can't get your bullet to open up and deliver shock waves, etc.; at least make a hole. Bullet expansion or not, bad guys generally don't like holes. Never forget: nothing beats shot placement - even if it's just a hole.
My snubbie defense load is a Speer swaged lead 158gn SWC HP. It's soft lead, and so it stands the most chance of opening up (not that I would expect it to). And it will mash and deliver energy if it hits hard tissue. That's the best I can expect from a 38 snubbie. My recipe is 6.0gn of Power Pistol; which is in compliance with Speer #14. It runs 921 f/s through a 4"bbl. I've never chronographed it through my snubbie for fear of shooting it.
(My "other" snubbie defense round is the factory Speer 38+P 135gn GDHP SB. Runs 955 f/s through the 4". I don't know what it runs through my snubbie, but probably fast enough to expand. That's what it's designed for - snub nose carry revolvers.)
As far as making ammo beyond SAAMI standard, I don't recommend it for small frame revolvers. Most modern small frames can handle some extra pressure, but I don't recommend it.
Keep your expectations realistic.
If you want to stick with using your 125 or 140 XTP's, I'd go with the 140's and stick with published data. I'd use a medium speed powder - my first choice would be Power Pistol. I just looked it up in Hornady 9th: Their top load is 6.7gns and yields 1000 f/s through their 4" test barrel - better than I thought. If you wanna go that way, start round 6.0gns and work up.