Yeah, pretty much. Any Steam Deck owner could easily tell you how the whole experience of the system is very much designed around using Steam. If you aren't a technical person, you can still figure out how to buy and install games directly from Steam, but running anything else will be some level of nightmare. Even installing pirated games is a big hassle.
Late to the party, sorry, but couldn't agree more. I was a hardcore pirate before the Steam Deck. Continued pirating for the first few weeks, but the whole process is so tedious and sometimes doesn't even work (especially great when installing a heavily compressed game for hours), that I quickly realised that it's not worth it. To give you an idea:
1. Download it
2. Copy it onto a thumb drive
3. Plug it into your SteamDeck and go to desktop mode
4. Add installer to Lutris (plus creating a new wine prefix, that needs keyboard input which is a pain in the ass when you only have the virtual keyboard available)
5. Run the installer
6. Installer won't run? Try another wine version and go back to 5
7. Install the game (keep the SteamDeck awake the whole time you fool!)
8. Installer crashed (hopefully at 99%)? Try another wine version and go back to 5.
9. Installer keeps crashing? Try bottles, heroic, or maybe install directly via Steam.
(10. Copy over crack)
11. Add the game's exe to Lutris (again keyboard input from hell)
12. Use BoilR to get your new game in the Steam Lib, hoping to NOT screw your lib (yep, happened to me for god knows why)
13. FINALLY RUN THE GAME - Whoops, doesn't work? Try another Wine version. Still not working? I guess you forgot to add some winetricks/protontricks, so please go back to the awful, non-communicating UI for that and try again. No luck? Congrats! You successfully wasted hours of your life. Well, sucks to be you I guess. Now have much fun with cleaning up that mess for nothing.
To be fair: this happened only a few times, most of the time it was working fine, however it's still too cumbersome for my taste, compared to hitting the "install" button in the nicely integrated Steam UI. And you could reduce the overall risk of a non-working game even more by going for repacks specifically made for Linux.
The worst part about it is that I actually started buying games on Steam only, before that (when not pirating, which happened rarely) I made sure to always buy it on GOG, but for these games you need to go through a similar process, with the addition of the obvious step 0: buy the game - or in other words: pay to go through that god awful process. (although that's only part of the truth, because you can add your GOG account to Lutris directly, which would skip some steps, but I still had to deal with step 6 onwards and stuff wasn't working for some reason)
That at least was my experience from months ago - has it changed in the meantime?