"the hassle of reinstalling all the apps and drivers...specially Microsoft office and Photoshop"
Installing Windows, making regional settings way I like those to be and installing Office take about one hour,
some more time for installing Photoshop (and another apps) when you need it first time.
Most of the drivers installed by Windows WU are OK, maybe manual install for Display adapter and printer.
"But What Is If upgrade to 21h1 Through The Update Assistant??"
You can try that first and see what happen:
A) It will fail because your ongoing update issues.
B) It will use only enablement package and doesn't fix your issues.
C) It will try use full build with same 'Can't keep apps' issue you have encountered already.
D) It will use full build, update completed and your issues are fixed.
You never know, just wait and try. Release of 21H1 should be quite close.
I Think It Is Better To Wait Now..
Also I Hope D (The Last Thing You Said Can Happen) Happens and Its Fixes All My Update Issues.....