It's happened. Sony have just updated the firmware for Sony a7s3 users and we can import custom luts

https://youtube.com/shorts/QCGZBSkHr5c?si=2wT081NJQ5EFkg6S

https://youtube.com/shorts/odVfynQOrNs?si=fu7I5rLmc2rlWda3

https://www.sony.com/electronics/support/e-mount-body-ilce-7-series/ilce-7sm3/software/00345067

please have caution when updating and read instructions carefully. 

peace everyone

Andy