No physical SIM was needed.
Just make your phone up-to-date (play store and probably FW, TicWatch had already newest Wear OS), install only Wear OS (don't install Mobvoi app). Follow pairing wizard (watch is brand new and not paired). Wizard will detect watch model and after few screens it will ask for eSIM (you are able to enter single line text only), enter eSIM in text format, and... that's all.
It worked for me like a charm.
Provider: Orange / Poland (eSIM, Flex traiff - officially Orange is NOT supporting this watch)
Watch: Mobvoi TicWatch Pro 3 4g/LTE (0403 / WH11013)
Wear OS: 2.24
Phone OS: Android 10
Phone Wear OS: 22.214.171.1243846678.gms
Phone Mobvoi APP: 3.20.0-1301.561
EDIT / ADDED:
Maybe you folks got a model for different market? Ieg. your in EU na you bought an US or Chinese version (or vice-versa)?
I'v bought my watch directly via www.mobvoi.com site and used EU/PL as location. For 95% there are different versions due to GSM capabilities/limitations... and they will not work on other markets.
Thanks Doman2011!! Maybe I´l try first your approach but I´ll could be wrong but I don´t remember to see nothing about the eSIM during the pairing process Mine was also bought directly via mobvoi.com site !!