I completely understand why this feels overwhelming, but before assuming the worst, I would really try to get a proper diagnosis from a dermatologist or hair-loss specialist who is familiar with diffuse thinning and DUPA.
Diffuse thinning can be especially difficult because it doesn't always follow the typical Norwood pattern, and it can also affect the donor area, which is why a proper assessment is important before considering something like a hair transplant.
And even when regrowth isn't fully achievable, there are still cosmetic options that can sometimes help reduce the visual contrast between the scalp and the existing hair. Scalp micropigmentation, for example, can be used in some cases to create the appearance of greater density without claiming to regrow hair.
But first I would definitely focus on getting the diagnosis confirmed and understanding whether your hair loss is stable. Don't make any irreversible decisions while you're feeling this overwhelmed.