To be blunt I would upgrade if possible. The tank barely looks like a gallon of water and is also quite tall, giving your fish very little swimming room (fish prefer horizontal space).
Normally the sides and gravel are cleaned during partial water changes, the gravel siphoned with a gravel vac. You would take the pineapple decoration out and siphon the gravel. The sides and tubing you could just wipe with a household sponge (a chemical free one that has never been used for anything else).
No need to upgrade your filter but that tiny tank will be a pain to cycle if you haven't already.
Hey there, you’ll be happy to know next month I’m moving to a 55 gallon. Unfortunately in my tiny current apartment this is all I could have. Thanks for the help!