The nice thing about using OBS is that pretty much every single configuration you can think of is supported and probably already figured out.
Using my focusrite 2i2 and OBS I was able to get my guitar > amp > focusrite > OBS and mic > focusrite > OBS setup in a few clicks.
This obviously is assuming you’ve got some sort of single device that supplies at least 2 inputs. However there are plenty of options if you’ve only got your amp hooked up to your PC and would need to communicate via headset or webcam mic. You can stream multiple audio sources.
And yeah I’d second the Twitch thing, with the only caveat being that music play during broadcasts is… ‘in a delicate state of affairs’ right now due to copyright litigation etc etc so, your/our mileage may vary with that using Twitch as the platform. Just something to keep in mind. I’m not sure how sensitive they’d be to me playing 10 second snippets of whatever (poorly) for 30mins lol