I don't know whether your domains would be locked but it's possible so I wouldn't take the chance. Any registrar where you can call or email someone and get a response would be better than Google. A lot of people recommend NameCheap. I don't recommend GoDaddy at all as their UI is full of traps and pitfalls to trick you into buying additional services.
All my domains are registered in google domains, if my account gets locked... will those domains also be locked?
Also, which domain register would you recommend besides google domains?
BTW: google domains is the only service I currenly use with a google account.