what's the minimum i need to run Persona 5 @ a stable 30 fps

If it supports TSX, that's an even bigger boost. Unfortunately, only a handful of CPUs can use TSX. In terms of recommendation, at least a 7th gen Intel should suffice. I use a mobile i7-8750H and it's been really good with Gran Turismo games surprisingly considering that the series is known to be graphically intense in the post-PS1 era.

I assume a Ryzen 7 should be enough, correct? I'm using a Ryzen 3 and debating upgrading to a 7 some day in hopes I could run Persona 5. This is probably a no brainer but I feel as though I should be sure.

With the recent AMD announcement I would definitely wait for the new Ryzen 5000's to come out and for people to post their RPCS3 experiences with them. It seems AMD will finally catch up to Intel in terms of single threaded performance so it will be interesting to see how well they will perform.