You can see with the Steam Deck. Valve is slowly releasing drivers over time but in early stages Windows was inefficient, sound didn't work or didn't work well, sleep wasn't snappy, the list goes on.

It had all the problems your average Linux install will encounter without the enthusiast-written drivers to work around manufacturers' lack of support.

That said, the Steam Deck seems to be the first non-enthusiast device where the manufacturer actually cares. Even laptops that get sold with Ubuntu preinstalled from the factory don't seem to receive that much support over the years.

I'd say pretty confidently that Lenovo has done quite a bit of caring over the years. I've had a bunch of T-series ThinkPads that have been super good under Linux.

This might have more to do with the glut of off-lease corporate ThinkPads being available at very competitive pricing for FOSS developers to pick up rather than any indication of Lenovo's commitment to FOSS.