Banjo burner

Nope.

No, because it simply isn't designed to do that. The regulator won't allow a high enough pressure, and the burner won't allow enough flow. You can make your own from plumbing fittings for fairly cheap (search for plans for a Frosty T-burner).

I'll also say that this is only really worth it if your firebrick is the soft insulating kind. Hard firebrick doesn't insulate and won't let your material get hot enough to forge effectively.

There are small propane forges available for as low as $80, and I think it would be worth it to save up for one. Even cheap ones do a reasonable job and will save you a lot of headache.

What you do is you use a sawzall or angle grinder to cut the ring off the burner. Like so you keep the orifice and venturi assembly. Then weld this venturi onto a stump of pipe so that it fits the normal forge designs.

Bigger problem you will have is that the regulator is only 5 PSI, limiting the power that is possible. Although I often use mine at only 3 PSI, I can turn it up as far as 30 PSI if I really need to make it hot.

Broke blacksmiths use charcoal forges: box of sand or a hole in the ground, bag of chunk charcoal, and a thrift store blow dryer. Cheaper, fussier than propane, it powered the Iron Age style until they used up all the forests and switched to coal.