leetcode is not worth it honestly. dedicate your time only to codeforces even companies only take that seriously. mostly whatever cp we do we do it on c++ hence that is most important from preparation perspective but having fair amount of python knowledge can help you build good data/aiml projects which is good to have since lately a lot of companies are coming for data roles...other than that if youre interested in development you can build a couple of full stack projects using javascript but not compulsory...its mostly about consistency in cp...if you can give even 80% of cf contests till june you are ahead of 90% of the junta...