Really difficult to actually get good numbers here since there's a ton of sampling bias and user agent strings (which are used for most of these market share detectors) don't capture Linux distros apart from ChromeOS.

But we can combine sources to get somewhere.

The Steam Hardware and Software Survey doesn't include any data on ChromeOS, because there's no Steam on ChromeOS, but it says that there's a total market share for Linux of 3.2% with the most common Linux Distro being Arch with a market share of 0.32% (probably due to the Steam Deck), followed by Mint with 0.24%.

So double the maket share to get roughly to the 6.3% total Linux maket share from PH, and we get Arch with 0.64% and Mint with 0.48%, which is both much much lower than the 2.4% of ChromeOS on PH.