What businesses are successful these days in small towns?

Every town needs a good chip shop.

My brother in law starting a side hustle as a photographer about a year ago as he wanted something to keep him busy when he retires young (army). He's always had an interest in photography, but he spent a bit of time practicing and reading up on it, bought the kit (camera, software, laptop, etc) and now he's flat out doing weddings and other smaller events. It's taken of in a way he never imagined (but he is good at it and doesn't take the piss on price). He's clearing a nice profit every weekend he does a wedding and it's something he can do well into retirement age to supplement his pension. Although the bridezilla type stories he tells are hilarious - his picture editing software gets well used to disguise cellulite, fake tan blotches, squinting eyes, too much / little cleavage, the odd extra kg or two etc.

Definitely a winner.

following on from my post above, this is probably an example of “quality sells”.

Id reckon if your shop was in my small town, it would probably thrive also- you’d always have a box of their ice cream in your fridge- special occasions, kids parties, absolutely they’d be involved - and as long as there’s good passing trade from other towns close by also, I’d say they’d do very nicely

A politician's constituency office.

Taxpayer funded, so guaranteed payment + heating and whatever other overheads.

Try target one of the political families as better chance of longevity in office.