mine ticwatch pro 3 Upgraded to development board.and i Extracted using terminal command bootLike said in the opening post, you can unlock bootloader, but only with do-it-yourself cable, like modified TicWatch S/E cable. Consult this guide: https://www.reddit.com/r/WearOS/comments/p3oj8i
Once you manage to unlock bootloader, you can try to follow this instructions: Post in thread 'TicWatch Pro 3 development' https://forum.xda-developers.com/t/ticwatch-pro-3-development.4312327/post-86176943
Of course, all you do is on your own responsibility
PS. Remember that rooting the watch can compromise OTA updates. Personally I did not root my watch