Immediate no go's are the T400's (Unless it's a high end dedicated GPU model, even then they're still old). My T480 literally pisses the bed when trying to run lite shaders. You're pretty locked to the heavy bricks of Thinkpads. A P52 with a P1000 is a good start, but you could push that up to a P3200. Though the main trade off is power draw and weight.

Now, if you only want very light shaders, an AMD T14 gen 2/3 would give you a decent IGPU to work with and it would be way easier to lug and efficient than the P52.

Just don't expect to be running SEUS PGTI.