I would offer looking more towards understanding architecture and systems design. How modern applications are deployed has significantly changed since many of these languages were designed and documented. Most tutorials will force the narrative inwardly, into language centrist processes and instruction, leaving really important design decisions/concerns entirely out of the picture.
Since you say you have a handle on TypeScript - that means you have enough conceptual understanding to really move to "any other web orientated language" with only mild idiomatic barriers to overcome. IMHO - learn about the concepts of microservices, api-gateways, "serverless" and similar. Then decide for yourself, what problem you'd like to solve - pick the language last
Edit: Since "employ-ability" is a desired outcome ~ python/dotnet/java/nodejs - no specific order of recommendation from me