I played around with upscaling PS1 games in retroarch last night and I was pleasantly surprised. There are some YouTube videos that talk through the process https://m.youtube.com/watch?v=6yDWYeuQ2pI
It can breathe new life into some dated looking games. Highly recommend giving it a try
I didn’t think to experiment with the shaders much, so I’ll give that a shot. I briefly tried the cell shading shader, but that looked way too unnatural for me – but it is neat.
(As an aside, I have my original PlayStation 1 and I really want to snag a real CRT at some point for some true nostalgia.)