socrfan1 I'm not entirely sure about the updates, but Samsung/Boost are usually pretty slow with feature updates (although the security patches are on a normal monthly schedule). I'm honestly not sure how feature updates are on locked vs. unlocked, though. FWIW, I did receive a Samsung feature update yesterday on my S10 that was being pushed out to all S10s.
As far as the SIM goes, I bought the 4-in-1 SIM kit from a Sprint store in my area for $3. Boost charges $10 for their SIM kit and it's the exact same as the Sprint kit. Make sure it's the 4-in-1 though, the 3-in-1 kits do not include the SIMOLW516TQ, which is the SIM needed for the S10s.