I have a plumbing question for yall

I would start by disassembling all the drain pipes under the sink and inspecting everything

I would go back to the vent pipe. Those things can be a bear. Are you using just a water hose or a hose with a pig on it?

If you push your plunger down and you can't pull it back up that means your clog is before the vent in that pipe or your vent is clogged and your have another clog past the vent. You should have a branch vent right at the drain going into the wall. When your pipe goes into the wall it hits a T, wet goes down vent goes up. Flushing your main vent isn't going to get that.

The horizontal portion of your branch vent should be several inches above the top of your sink (Can't remember the number off the top of my head). If your branch vent is below the top of your sink your branch vent can clog and you essentially have an unvented drain.

I'd pull the pipes out and see if you can get your auger turned up into the branch vent and see if you can find a clog in the vent.

Remove the p trap and drain pipe into the wall. Then use a Drain king. Shove it as far into and own the pipe in the wall as you can. Check your tub drain for sound of water flowing by. Might want someone to verify no water comes out of any vents as well. Might want a bucket in the event some water leaks out before it can seal around the pipe.

Sounds like a major clog in the drain line before the vent. If it was just a clogged vent, then the sink would drain but suck the trap dry. Since there is a vacuum when plunging, the vent cannot communicate with the sink - it it could, there would be no vacuum. Try fishing into the drain pipe with trap removed.