u/Current-Chapter9420

is this salvageable?

okay for context we've never actually used this oven since we got it in 2024 and used it as a storage for leftover foods for the day. and now i got into cooking and wanted to use it but i don't know how to clean it?? I read about using baking soda and vinegar but I've yet to buy the former so haven't tried it. i tried using an all purpose cleaner though. it did clean some stuff. but there's still this gunk and wont come off. is it rust?

(the pics are after using the all purpose cleaner)