They sell stuff like this to help with couch scratching. Also, having many scratching posts around and regular nail trims help with this too.
Cats won’t mind going up stairs to use litter box. If they are older with mobility issues then this could be a problem.
Go to a local animal shelter
just thought of something. a coral feeder could work for you https://www.amazon.com/Acrylic-Accurate-Anemones-Aquarium-Organisms/dp/B087BYDGQD/ref=sr_1_3?dchild=1&keywords=long+pipette&qid=1627614238&sr=8-3
It makes a very fun hobby, though.
https://www.amazon.com/Awarded-2018-Best-Compound-Microscope/dp/B0094JTZOU/ref=sr_1_4?dchild=1&keywords=omax+400-2500x&qid=1617814337&sr=8-4
Not terribly expensive!
All: https://www.amazon.com/Awarded-2018-Best-Compound-Microscope/dp/B0094JTZOU/ref=sr_1_4?dchild=1&keywords=omax+400-2500x&qid=1617814337&sr=8-4 This microscope will allow you to see the same stuff. $200!
Iseebiz Automatic Cat Feeder 3L Pet Food Dispenser Feeder for Medium and Large Cat Dog——4 Meal, Voice Recorder and Timer Programmable,Portion Control https://www.amazon.com/dp/B0772VBL12/ref=cm_sw_r_cp_api_glc_fabc_Y5s-FbY5MDN8H
OH YES rabbitproofing is a thing. Split-length tubing like this can be great for cables that can't be moved out of the way: https://www.amazon.com/Black-Split-Loom-Tubing-SLT38-15/dp/B004RIMPDG
This is a special cat hammock with a stand. From the side it looks like this: https://www.amazon.com/dp/B07PZ1S3V2
And from above it seems like a flying towel))