OP here. I found two lists of supported languages on their site: The dropdown in their code editor which is reproduced in full including both python versions, and a list of environments which includes things like bash and "vanilla js" or ECMAScript which I added to the first list.

https://support.leetcode.com/hc/en-us/articles/360011833974-What-are-the-environments-for-the-programming-languages

In reply to Re^2: LeetCode's ignorance of Perl by Anonymous Monk
in thread LeetCode's ignorance of Perl by Anonymous Monk

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