I literally just googled "Steam hardware survey"

Btw, for some reason I can't view that image. Tried in 3 browsers on my phone...

   https://store.steampowered.com/hwsurvey/Steam-Hardware-Software-Survey-Welcome-to-Steam

I came back and found the difference. You clicked "Linux Only". But I'm glad you did, because it gives us additional information helping us actually answer the previous question more accurately. Strongly falsifying the earlier conjecture that they were mostly SteamOS. We can see only a third are. 2/3rds of Linux Gamers are NOT using SteamOS (definitely a subset of SteamOS users are also not using a Steam Deck)

  "SteamOS Holo" 64 bit                             33.78%    -0.70%
  "Arch Linux" 64 bit                                9.45%    -0.23%
  Freedesktop SDK 24.08 (Flatpak runtime) 64 bit     6.41%    +0.15%
  Linux Mint 22.1 64 bit                             6.20%    +0.89%
  Ubuntu Core 22 64 bit                              4.62%    +0.23%
  Ubuntu 24.04.2 LTS 64 bit                          4.44%    +0.26%
  "Manjaro Linux" 64 bit                             2.61%    -0.05%
  "EndeavourOS Linux" 64 bit                         2.46%    +0.06%
  Debian GNU/Linux 12 (bookworm) 64 bit              2.27%    -0.08%
  Pop!_OS 22.04 LTS 64 bit                           2.23%    +0.02%
  Other                                             25.54%    -0.53%

  https://store.steampowered.com/hwsurvey/Steam-Hardware-Software-Survey-Welcome-to-Steam?platform=linux