I have a quick something to say - you say in the tutorial that no texture in Doom looks 'shootable' - that is no longer the case, thanks to John Romero. In Sigil, Romero uses the "evil eye" object as a shootable switch - and great majority of Doom players played at least the first level of Sigil because Romero is basically a celebrity in our community.
So, we can totally make the Evil Eye new standard for shootable switches.
Here is the thing I'm talking about:
https://imgur.com/a/ePW03NV