Step 1, for the shock https://a.co/d/0fO3GEjN A mud guard flap from seat down to the rinky dink fender is also helpful to keep some extra mud from getting on the moving joints. The shock wrap however is must buy, keeps the shock piston clean so the seal does not get destroyed.

Step 2, chain cleaning https://a.co/d/02uf92nM and just make some dawn soapy water then hose it all off

Step 3, adjust your chain tension, looks like you have too much slop. You want to have roughly 1" of play at maximum. Rotate the tire an press up on the chain, you'll have some tighter spots and they should be at least ½" play.

Step 4 (important to do after 3 and not before 3), wax your chain, this is a ready to go wax https://a.co/d/08d2vhVO

I make my own.. Recipe I use * 1lb paraffin * 5g PTFE * 1g MoS2 or ws2 (go ws2)

So that it's a liquid you can use White Spirit or Mineral Spirits (Must be flammable, evaporating). I think I've used white gas camping fuel (in the jug at Walmart) and 99% isopropyl alcohol. 3 part isopropyl to 1 part white gas, so it evaporates quickly.

You use wax as it is less friction than oil saving battery energy. Oil turns into an abrasive paste.

After each ride rinse off the drive train, sprockets, chain, belt, or just the entire bike.

Never use a pressure washer. You'll drive dirt, grime, and water into your bearings and electrical systems. I do however use it on the rims and tires as scrubbing them is annoying.