Unlocked units XDA thread: https://forum.xda-developers.com/t/op7t-oos-10-0-15-hd65aa-ba-unbrick-tool-to-restore-your-device-to-oxygenos.3994835/

Specific notes:
In global MSM tools, there is a target button.
Selecting "O2" as target should give you the global firmware while selecting "India" as target should give you the Indian one. See https://i.imgur.com/2ipNyIy.png

T-Mobile variant XDA thread: https://forum.xda-developers.com/t/op7t-t-mobile-oos-10-0-10-hd63cb-unbrick-tool-to-restore-your-device-to-oxygenos.4004005/