Guidance for ML breadth/Fundamentals

I have had my fair share of playing around with different Kinda off generic Ml models and projects but It had been mostly random and not organised. So now i want to dive deep into some niche in this field maybe even understand some relatively easy research paper and work on it too. Before doing all that I still want a very good base in the fundamentals. So as an experienced person in this field or a skilled student or a tutor do you have any suggestions for me maybe some resources which i can use . Also i must say that i am not planning to spend a lot of time(at most a month) for clearing the fundamentals as i am aware of most of the stuffs and wish to focus more on a specific concept as quickly as possible. A fast paced onto the point approach will be really helpful. Are statquest videos good enough for this ? Also i will really appreciate if you have anything else to tell me beyond what i asked for. Thank you.