Another programming language as reference. I can learn a new language really easily this way, but the first was really hard - it was so unlike anything i had ever done before.
“Writing Fortran in Lisp” should not be disregarded. There’s a lot of value of having hands on exposure and success with common, even if not idiomatic, concepts.
Ye Olde “write once, throw it away” concept. Using prior language knowledge can make the first steps much smaller as you learn not just the new language, but environment and tools.
This can give you a quick, solid foundation with which to leverage learning newer ideas and idioms of the new system.