Hello and welcome! There's an advocacy group I like that offers some tips for choosing bikes (and other gear) for heavy riders. Here's a link to their page on bike selection:
https://www.allbodiesonbikes.com/biking-for-big-people
I'll throw my two cents in for Surly. Like all bikes, they can be tough to come by these days, but they offer a wide range of sizes compared to some manufacturers. I personally wouldn't worry about riding any of their bikes at your weight. They can be found used, but they aren't super cheap new or used.
On the budget end, I think Polaris OBark gave really good advice. Smaller mountain frames should be plenty strong (a 175 pound rider going off jumps is stressing a bike more than a 320lb rider on the road), and they're readily available. That might be a good entry point to cycling. Save your money to make a bigger purchase if/when you really fall in love with cycling and know what you want. Unless you're planning to ride off-road (not pavement or dirt paths), I'd avoid suspension.