I can understand the desire to ride but I’ve never been as heavy as you. I topped out at 260.
Not giving you a hard time but the consumer market just isn’t built around bikes that can support you. I saw you had a Worksman and was wondering if a 7 spd base Worksman would be the bike you need to start with until you get down a little but you would know that more than others.
I do have a Mongoose Dolomite (ALX aluminum frame) and can attest to some of the lower grade equipment. You get what you pay for and I felt I paid for a good base with some meh components. I think the other mongoose bikes Argus or the Framed would have better equipment but the frame and wheels are your issue.
in my case I replace the touch points seat, stem grips and pedals to get the bike to fit better and ended up with a nicer bike for it.
after riding it a bit for 8 months nothing has failed but I want a few other things because I just want nicer. The brake levers are cheesy and I picked up some Shimano levers. And while I had no issues with the shifters I didn’t like shifting up and down with my thumb and just got some Shimano Rapid Fires. Again the stock stuff worked just I wanted a little better.
All that said I don’t think these bikes will support your weight. Maybe at 300 lbs but currently I think you will just be setting yourself up.
Another thought is a Trike, either a Worksman or a Sun. Hope that helps.