you can unlock your phone carrier (EE) but the software will always come from them as the CSC of the phone doesn't change.
Waiting for updates can be frustrating but Normally the frustration comes from waiting for the manufacturer to release it, atleast if you know they have released it in a few days you will recieve it. it can also be a benefit as the one previous to the latest had issues which were resolved in the latest one and your phone will never get those issues because it was pulled before you recieve it.
also worth noting that most updates (all manufacturers) don't introduce new features and just fix small issues, so it's not worth all the FOMO that we get