Would PDO be effective if Sculptra had no effect on me?

Nothing, not even threads, lift the face at all, not even a little. The companies that make PDO threads and the 'healthcare providers' that market and use them are all involved in fraud, and are relying on the placebo effect to con you into thinking there was a result. We learned 15 years ago that permanent threads had no effect by 6 months; it's not any different for resorbable threads. Volumizers like hyaluronic acid gels (Juvederm/Restylane/etc), Sculptra, Radiesse, and Bellafill don't lift either, and are the primary agent for making someone look bizarre when used in excess. They are great when used properly, but when a lift is needed, nothing else will suffice except surgery.

It's true that Sculptra and PDO threads are similar (being the materials of dissolvable stitches), however they have different chemical structures and behave differently in the skin. I think the difference between them is worth trying PDO threads despite lack of response to Sculptra.
I'm also wondering how long it has been since your 5 Sculptra treatments were placed? It typically takes at least 3 months to see any difference and at least 6 months to see the full effect. At that point, results last at least 2 years (according to clinical studies). Comparing high quality before and after photos is especially helpful to see the change in fine lines and hollows/folds being improved with Sculptra, since the changes take place so gradually as you look at yourself in the mirror daily.
It's also worth noting that Sculptra revolumizes and improves skin quality drastically, but may not provide the lift that is ultimately your goal. However, it can properaly prepare your skin for a more effective PDO thread lift. It's common for people to truly need both modalities to reach their aesthetic treatment goal of lifted cheeks and jowls. Without Sculptra, PDO lifted thinner skin isn't as youthful appearing as when the skin has been rejuvenated with Sculptra first. Sculptra treatment also provides more texture within the skin (increased collagen fibers) for it to grip the PDO thread when it's placed. When the skin is thinner, it's more likely that the PDO thread may not hold as well, and you may be disspointed with your PDO thread results at that point or require more threads placed to reach your goal.
As far as difference in chemical structure. PDO threads are made of polydioxanone, whereas Sculptra is made of PLLA. PLLA is Poly-L-lactic acid. They are similar with both being dissolvable stitches in the body. PDO typically dissolve faster than PLLA. PDO stimulates collagen growth for about 3 months while Sculptra does so for 6 months.
Bottom line, give it a try, combining these two treatment modalities may be the key to reaching your goals!

Dear Christalent,
I have responded to your other question and can only answer in general as I have no direction in the results you are trying to accomplish nor any idea what facial issues you are concerned about. Please:
1. Consult with a talented and artfully skilled Board Certified Plastic Surgeon for a hand-on evaluation and which of the non-surgical, minimally invasive and surgical options are best for you.
2. That said, consider
a. Non-surgical Retinoids for skin turnover and collagen stimulation and then mid-depth TCA peels.
b. Minimally invasive: Sculptra for firming and tightening (not as you mentioned volume and lifting)
c. Minimally invasive: PDO or PLLA barbed thread suspension sutures for lifting; BUT the amount of collagen production throughout the face is minimized due to the minute thinness of each thread. Intradermal PDO or PLLA thread meshing will provide a better resistance and wrinkle reduction.
d. Surgical lifting.
All the best with your rejuvenation journey.