Well it would be helpful if you posted the right way to do things then. Or at least discuss specifics on my plan.

I always thought double vapor/water barrier was bad

I look forward to building a home some day with perfected water management and continuous insulation exteriorly too. Cheers

So should I only seal the rim joists and accept it as enough to help with air leakage and call it enough? I bought the house from family and there’s never been any bulk water issues for >10 years. As far as vapor goes, is there anything I can do to allow the concrete block walls to still dry to the interior? Mineral wool bats mechanically fastened to the walls? Since air penetration through the walls is minimal.

I can’t envision any significant open air gap behind the rigid insulation allowing the insulation to be effective thermally

Hoping there’s an adhesive I could bond the rigid insulation to the plastic panels. If it’s plywood, you make a good point. Maybe I should use 1x2 furring strips with concrete anchors, then the rigid foam, then the plywood. That would allow for secure ways to attach shelving for myself and future owners without having to go down the concrete anchor route again.

Fair enough. I just can’t afford to excavate around my entire house and do it again right. This won’t be a forever home just a “for a while home” and want to make it more thermally efficient and comfortable place. I don’t have a ton of extra head room so I was likely going to not insulate the floor. If I do end up doing it at some point, I’d make sure I’d seal the floor to wall transition. Since I’m not insulating the floor, is there benefit to placing a sill gasket or other type of thermal break below the rigid wall insulation?

If the dimple mat wouldn’t be ventilated, I’d probably just forego it then as an unnecessary cost increase

I don’t necessarily want to frame a wall in over the top. I was hoping be able to do just rigid insulation on top of a dimple mat if helpful and then an FRP (fiberglass reinforced plastic) panel or something similar on top of that. Maybe plywood. It’s not ever gonna be a completely finished space. I just want it to be insulated