Most here simply work with fT4.
Injecting hCG would be inconvenient? Your current state is inconvenient. You get to choose a new devil instead of the one that you know.
cholesterol → pregnenolone → DHEA → Testosterone —is the chain, highly simplified.
Fixing ones HPTA is sometimes possible, if you can find a correctable problem that can be fixed.
Hemochromatosis Iron overload - Wikipedia
Can also be a factor.
You can do a SERM trial. If that does not increase T levels, then there is no reason to expect that the problem can be fixed unless a vein defect of the testes can be found and corrected. Typically that can ache.