I forget the name of the company but there is an Irish company broker that seems to be the main player in broking deals of this sort.

If you ask at the Indiehackers forums someone will know which company I mean.

Is it FE International? My only awareness of them comes from patio11, who speaks very highly. (And I enjoy getting their newsletter that lists properties for sale...)

https://feinternational.com/

Yep that's the one.

And to browse cool shaders: https://www.shadertoy.com/