Can someone help me figure out what it even is I'm trying to do? I'm a tech savvy kinda persons and if someone just gives me the general idea/right keywords to search for I can probably figure the rest out myself, but I'm caught in a real X/Y problem.

JUNK: Arch, KDE (X11), 3080 (proprietary drivers), OBS, Elgato HD60 X, 3440x1440 ultra widescreen

I just want to do some simple streaming to Twitch/Youtube and game recording.

The Elgato obviously doesn't support my ultrawide so my original thought was to leave the UW monitor plugged in with DisplayPort (as it already is) and then plug in the Elgato with HDMI and then switch the monitor input when I'm ready to stream. The UW stretches the 2560x1440 out though, how do I configure the viewport to keep the proper aspect ratio and put black bars on the side? Alternatively, can I configure the UW to 2560x1440 with black bars and simply mirror the display, or will I take a performance hit when streaming like that? And how do I change the xconfig on the fly, is that something I'd want to write a script for?

I inherited the Elgato from a friend who gave up on streaming and while I'm not entirely opposed to spending more money on potentially more appropriate gear ....... I'd really rather not.

Like I said, if someone can just explain to me what I should be doing and give me a swift kick in the ass towards the right direction, I can do the heavy work of putting all the pieces together, I'm not looking for a total solution 😵😵‍💫 Thanks!