Overkill is definitely something to watch out for at this time, since a powerful GPU makes a difference essentially in the Develop module only, and not even all of it. One source of GPU information is Puget Systems, who have run a number of tests in Lightroom Classic using a range of PC hardware. Go to the link below and read the section Video Card (GPU).
There's little point in an expensive gaming card (GeForce or Radeon). Beyond the midrange there's little if any return on investment.
The main problem with all these cards is buggy drivers, not lack of nominal performance. The drivers are released to keep the gamers happy and let them run the latest games. So they cut corners, and fix the bugs later.
NVidia Quadros and AMD Radeon Pros are not made for gaming, but for graphics, 3D and CAD. They are more expensive for similar specs, but generally a lot more reliable.