Is this upright regrow hair (good hairs regrowth) after a huge effluvium? (Photos)

This is tough to answer without an in-person evaluation. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone that can help regrowth. See an expert. Best, Dr. Emer

These do appear to be upright regrowing hairs. I'd need to see your scalp myself to confirm, but they sure do appear to be URH.  However, one can not assume he or she will get your density back to 'normal' after a massive and prolonged shed. Of course most do, but some don't.  With hypothyroidism especially, the improvement can be incomplete. For many these reasons are due to AFMPS which you can read about in the link below.  You will known in 9-12 months if your density will return to normal.

The pictures you are showing demonstrates significant miniaturization of the hair suggesting an on-going problem