Wouldn't recommend .22lr, but as other have said, it may be better than nothing. Look into carrying Federal Punch ammo. It's pretty much the only round that will consistently penetrate ballistics gel the 12-16" out of a hand gun. You may also want to go with something that has a longer barrel to get the most velocity out of the round.
The trick is to allow enough non-compressible fluid into the cavity to disrupt the bullet/jacket. Will silicone allow for that under various conditions, hard to tell. It appears to me that the "insert" that Hornady uses is slightly more rigid than your average caulk. I would probably try to replicate the durometer of what they use as closely as possible, since I'm sure that they went thru many test cycles to determine what works best. IIRC, the Critical Defense bullets also have a different jacket to enhance expansion.
I can guarantee you it won’t be easy to turn it into jack shit. The digital part may be new, but we’ve done the backed by a physical item thing, and it’ll be a mess. There’s an inherent issue with pulling enough of a thing of value out of the global economy in as volume large enough to represent the global economy.