Just use Square’s Cash App! Free stock trades AND you can buy fractional shares AND a bunch of other stuff like P2P payments and bitcoin. I work there and so can say with some authority that we can handle more volume without going down than RH can.
Here's some more inside info ...
If your "financial app" provider doesn't have a banking charter, run. None of the recent trendy fintech companies have a charter, and are thus clown cars.