If you want to just dock your SteamDeck and use it as a daily driver, that is possible, because that machine is quite capable. Ive used it like that before; and with a monitor, external keyboard and mouse you wouldnt know the difference to any desktop linux machine.
If youre unfamiliar with Linux, I wouldnt necessarily say you should switch distros, SteamOS is fine and usable, but it is true their version of KDE Plasma - the desktop environment outside the game mode - is outdated (SteamOS uses KDE Plasma 5.27, and the current version is 6.2), I hope Valve updates it soon.
Otherwise, if your needs for a PC include gaming (minus the things that dont run on the Deck, of course) and regular everyday usage, you should be fine. However, when we're talking more specialised software, like the Adobe Creative Cloud, or some other professional software that is Windows- or MacOS-only, then you might wanna keep your Win/Mac install.
But if you dont need any specialised software, I'd say just give it a try!