
Samsung Gear S
The latest firmware for Samsung Gear S (SM-R750) is R750XXU2BPF1 with Android 2.2.1.3, released on June 12, 2016 for 9 regions (CSC). Every official firmware build for SM-R750, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/R750XXU2BPF1
All 23 builds in our database run Android 2.2.1.3. The newest build, R750XXU2BPF1, was released on June 12, 2016. No new build has appeared for 126 months, so regular updates for this model have most likely ended.
Box codes of SM-R750 for different colors and markets. Firmware is chosen by the model code SM-R750 and your region (CSC), not by the SKU.

SM-R750J

SM-R850N

SM-R765N

SM-R855F

SM-R640N
The newest firmware for SM-R750 runs Android 2.2.1.3: build R750XXU2BPF1, released on June 12, 2016.
The latest build for SM-R750, R750XXU2BPF1, was released on June 12, 2016 (10 years ago).
SM-R750 has had no new firmware for 126 months, so regular updates have most likely ended.
Yes, all firmware files for SM-R750 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-R750, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SM-R750.