I have a t480 with an mx150 graphics card. I run Zwift on high and have pretty good luck although it can stutter when going through dust. Running on medium might help that but the suttering is momentary and doesn’t bother me. I also weighed the AMD options at the time, which was the 485, but there was a lot of talk about the amd mobile chips not running at their full potential so I went with the t480.
I personally use the laptop for work, which is why I wanted a Thinkpad, but I wanted something that could run Zwift too. There is a Thinkpad with a gaming card in it that you could look at too but I think those are around $600 more.
I just figured that if I really needed a better graphics card,I would use the thunderbolt connection and get an eGPU. Been using it for a year and it’s been great. Never a crash and the graphics are good. Not full blown gaming card good but better than appletv.