Frustrated with my Nikon D3500 and looking for advice on upgrading

Got it last summer and been having and absolute blast with it, got a macro tube and a bigger 55-300 lens to play with. But time and time again I keep running into annoying little limitations.

This model doesn't have a shutter release input thing, so remote shutter is locked behind a falling apart android app>bluetooth connection. There's a tonne of small little things like this that I wish I looked into before making the purchase

Essentially - right now I'm thinking that I want to upgrade the actual dslr before investing any more into lenses, but I'm a bit too out of touch to know what the good models to go for 2nd hand or whatever.

Are there any tildoes out there that have some experience with older but capable bodies?