I bought Doom on Switch and have never played it in portable mode.
Let's not beat around the bush, your post was misleading. Not only did you not specify "in portable mode" in the OP, but as the game has a dynamic resolution, calling it an anything-p game is inaccurate. You should at least amend your statement to "can drop to SD in portable mode".
You bought Doom only because you don't have any other current gen platform.
The lowest common denominator decides if a game is viable on a platform. Scalebound was cancelled because it wasn't possible on Xbox One, even though it may have been on Xbox One X. If a game cannot run on Switch portable mode, even if it could run if it was exclusively playable in docked, it still wouldn't be ported. Its why mentioning resolution of a game on portable mode is of direct concern.
Doom has dynamic resolution on every console, and yeah the game is generally 576p on Switch and can go much lower. The settings are also lowered a lot, as its below the lowest PC settings where other consoles have combination of medium and high settings. The alpha effects are rendered at just 360p and the game still struggles to maintain 30 fps. Still it does put into question if Devil May Cry can be ported to Switch. I feel its possible but hope they don't have to cut too much from the game.