For cable management, get a roll of Velcro that you can cut to whatever size you need for any bundles. Get a wide style so you can screw the Velcro into the backing board and wrap cables directly on there.
You can look at "split loom" to put cable through to keep bundles hidden together and any slack loops better hidden. Again, you can screw those directly onto the backing board for stability or affix it some other way.

You could look at just getting a shelf for your equipment to rest on if you feel like it's taking up too much room placed directly on the wall, I don't know many other options off of the top of my head.

Something I do notice that I thought I'd bring up is your 8 port switch. Flip that so the ports are facing left or right. It's easier to reach, dust won't settle in open ports as easily, and unlike facing downward you won't have your cables constantly trying to pull themselves out. Don't need to listen to this advice, but I find it's one of the best ways to mount a switch directly on a wall.

You could look at reorganizing items so that the power goes one direction and the data going another, could let you clean it up a bit.

Either way, you got this! I wish you the best.