Can I have PRP treatment and use Viviscal to improve donor area before Hair Transplant to avoid Finasteride?

It is best to ask your surgeon about post operative care as each doctor has their unique regimen.   In general there is no conclusive proof (at least not the ones accepted by most doctors) that PRP works.  Finasteride does not help with transplanted hairs and it does not stop genetic hair loss completely.

Finasteride is likely the best way to improve your donor area. Whether or not PRP works is debated. You of course can try it and the other methods you listed but their results won't be as reliable as Finasteride. Keep in mind that 4500-5000 grafts is a lot for one surgery, and it may be worth your while to have a surgery with however many grafts your donor area can spare now, see how it grows, then consider a second round after building up your donor area if you're still unhappy. After the first round you may be pleasantly surprised.

Actually there is no way to improve donor area. Using  viviscal and PRP treatments also dont work about that purposes.Number of grafts in donor area is related with your genetics and you can not improve or increase the number of it. plus , it is almost impossible to get 4500-5000 grfats in one single session of operation /harvesting period.ıf you make strong hair by using finasteride and  doc use them for hair restoration ,  you lost all these weak, finasteride reinforced  hair in d future.

In a very small subset of patients, using finasteride or PRP can help the donor area. PRP sessions are typically scheduled no sooner than 6 weeks apart. When planning for a hair restoration, your donor area may not have enough hair to cover your entire head or all of your loss over time, and when dealing with a limited donor situation, one must be careful not to over harvest the donor area. In this case, you should be sure to focus on the front area as this is the area that people see when they interact with you. You can also consider having scalp micropigmentation (SMP) done in both the recipient and donor areas. 

PRP is excellent treatment option to enhance thickness and density of hair loss. PRP sessions should be spread out by months not weeks to maximize the benefits of the procedure.

The donor area is resistant to medications of all types and should be strong in any event. The use of finasteride is valuable both before and after a hair transplant as this drug will prevent shock loss, see below