What Specialization after the course in Generative AI with LLMs

Hi all, I’m a CSE and in 2018 I completed the ML course by Ng on Coursera.
Afterwards, I lost interest in it, but Generative AI has been blowing my mind over the last few months.

After 5 years as a .NET back-end dev I’d like to become proficient in using Generative AI technologies to flexibly customise models in different contexts.
I currently work in the fintech industry, but applying LLMs to theoretical physics research is what attracts me the most. To apply LLMs to theoretical physics I was thinking of enrolling in an online university to gain some credibility, but this might take a very long amount of time.

Nevertheless, what specialization would you suggest after completing the course in Generative AI with LLMs?

Thank you in advance for the attention!