
Samsung Samaung Gear Fit
The latest firmware for Samsung Samaung Gear Fit (SM-R350) is R350XXU0BOA2 with (Android N/A), released on March 30, 2015 for 61 regions (CSC). Every official firmware build for SM-R350, 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/R350XXU0BOA2
The newest build, R350XXU0BOA2, was released on March 30, 2015. No new build has appeared for 140 months, so regular updates for this model have most likely ended.
Box codes of SM-R350 for different colors and markets. Firmware is chosen by the model code SM-R350 and your region (CSC), not by the SKU.

SM-R540N

SM-R640N

SM-R630N

SM-R420N

SM-R530N

SM-R900N

SM-R910N

SM-R840N
The latest build for SM-R350, R350XXU0BOA2, was released on March 30, 2015 (11 years ago).
SM-R350 has had no new firmware for 140 months, so regular updates have most likely ended.
Yes, all firmware files for SM-R350 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-R350, 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-R350.