Go with a third party monitor, you’ll get way more bang for much less bucks. I’m using a ViewSonic VA2756 UHD with a MBP M1 Max and it’s a beautiful monitor. I do some film, mostly TV broadcast (retired TV producer). It works fine, and was a fraction of the cost of an Apple monitor.
Any new Mac will blow away what you have now, but bear two things in mind.
1- Get as much as you can afford (32GB RAM is plenty) CPU wise, cause it’ll age out later rather than sooner.
2- Verify all third party software and plugins will be compatible, or you have something to replace them with if not. Don’t get cause updating FCP Libraries and find third party stuff not working.