Do you still get Promo if you don't Pre Order on Samsung.com?

Yes. You usually have to upload a pic of the proof of purchase as well.

Actually for the last couple of phones (Note 9 and S10+) I didn't even need to upload the proof of purchase from T-Mobile. The Shop Samsung App was able to get the IMEI and other info directly from my phone and validate my claim in short order!
 
Actually for the last couple of phones (Note 9 and S10+) I didn't even need to upload the proof of purchase from T-Mobile. The Shop Samsung App was able to get the IMEI and other info directly from my phone and validate my claim in short order!

Good to know. I haven't had a Samsung phone since the S8+. Glad they've simplified the process.
 
Correct. Reserved pre - orders on Samsung got 50 extra bucks. I believe pre-orders now are both the same on Samsung and retail (100 or 150 depending on the model). Trade-in promos are also higher directly on Samsung.