How long will it take for a react native developer with 5 yoe to become fullstack ?

How long will it take for a react native developer with 5 yoe to become fullstack ?

EXPERIENCED FULL STACK DEVS PLEASE ANSWER THIS !!!

Guys recently I have been thinking about becoming a full stack developer and learn it . How long will it take for me to learn ,I am working as a react native dev(mobile) for last 5 years. I can spend like 1 hour daily or maybe just weekends to learn it as I am working professional.