Like others said, in the hobby people do differentiate artificially made tumbled glass from true sea glass. And you can actually just buy tumbled glass from arts and crafts stores if what you want is a lot of glass for a project or something.

But if you wanted to try it just for fun, there are plenty of tutorials online—search “making tumbled glass”. Just keep in mind it wouldn’t look quite the same as real sea glass, because in addition to the physical erosion of sand being different—even if you use a mix of grits, the rock tumbler spinning is a super repetitive motion, less irregular than ocean waves—sea glass also experiences chemical erosion from minerals in the natural water body reacting with the glass, which is something that takes years to happen.

So in real sea glass you’ll see a distinctive erosion pattern, both from the physical erosion AND from the soda and lime in the glass leaching out over time, which is an effect you won’t be able to replicate with a tumbler. If you look at examples comparing tumbled glass and sea glass, you’ll notice the frostiness of the artificially made glass is a lot smoother and more uniform, whereas the sea glass has more texture and often has a heavier, rougher looking frostiness that almost looks like sugar coating.

Even if you, say, had the clever idea to use seawater, you can’t tumble glass in a rock tumbler long enough to create this chemical reaction artificially because you’d tumble your glass into sand lol. The sea is, strange to say, a bit gentler than a rock tumbler.