The simplest lo-tech way is to simply talk on something like messenger or what’s app and allow your collaborators to remotely log into your computer with anydesk. I don’t think they will hear audio, or probably not in sync, but you can see their cursors. You can’t show the image without the GUI. Anything that shows just picture will probably need a piece of hardware that taps off the SDI of a broadcast monitor or a graphics card with an SDI output. Options involve complexity and complexity involves cash, so you need to find your comfort zone on that curve.
Yeah you’re likely going to have to give up on letting other people draw on the screen and just use voice comms to tell you what they want unless you want to start forking out $$$.
You also can stream your broadcast output into some laptop (if with your setup possible) and then screenshare that within zoom from the laptop. During the lockdowns that worked fine.
I usually do this using google meet… joining with my linux box in presenter mode and with my ipad in companion mode… works pretty well… no laserpointing though… Been using Dropbox Replay for that…