A blow torch might be worth trying. I'd think it's still not as good as a hot broiler because it's heating a relatively small area.

As noted in an earlier comment of mine, I have one (actually made for burning weeds) connected to my gas grill tank, and a fancy Japanese one inside. They're honestly pretty rinky-dink. What they are good at is transferring heat just to the crust. But they only do a small patch at a time, and you have to hover for far longer than you'd think. Like, you do a little patch, leave the torch there for 30 seconds, move on. They just don't pump enough energy into the crust fast enough for them to be a general solution. I use them for touching things up, or crisping up a bit.

You tried an actual hardware blowtorch. Thats never failed me, though these days I just finish on a ripping hot stainless steel skillet.

I feel like I am better off with cast iron or stainless steel compared to slightly bigger torch. Stainless steel allowing some deglazing for sauce. Torch is still too small area and burns more so sears.