What languages do you know currently? This will probably be an unpopular opinion but unless you know more than you can count on two hands, it's unlikely that Rust or Go will be give you the best ROI if your focus is career enhancement. The largest career ROI is probably in getting to advanced-intermediate level in a couple of the following (in absolutely no order, I intentionally put ones I don't know first):

- Python

- Ruby

- JavaScript

- PHP (especially for WordPress if your focus is web)

- C#/F# and the .NET ecosystem generally (especially for corporate)

- Java (especially for corporate)

- VB.Net if you want a government job

- C/C++

- Enough SQL to do whatever you want with the above