SM-N975U vs SM-N975F - the U in SM-N975U stands for USA.
The device page https://doc.e.foundation/devices/d2s lists
SoC Samsung Exynos 9825
Models Supported
SM-N975F
Other models are not supported
I ran a search SM-N975U vs SM-N975F and came up with https://www.gsmarena.com/samsung_galaxy_note10+-9732.php.
Chipset Exynos 9825 (7 nm) - EMEA/LATAM
Qualcomm SM8150 Snapdragon 855 (7 nm) - USA/China
I don’t have first hand experience of the device but the traditionally locked bootloader in the Qualcomm Chipset will be the fundamental reason the USA model is not supported.
Double check with device codename
Samsung,Galaxy Note10+,d2q,SM-N975U
Samsung,Galaxy Note10+,d2q,SM-N975U1
Samsung,Galaxy Note10+,d2q,SM-N975W
Samsung,Galaxy Note10+,d2s,SM-N975F
USA users have warned against Samsung due to proprietary VoLTE issues. Know your hardware - Samsung
During 2022 USA Carriers moved to VoLTE. Samsung’s implementation of VoLTE is proprietary and has not so far been reverse engineered for custom ROMs