Here are some handy links (for me) that might help you out too:

https://nim-lang.org/blog/2020/10/15/introduction-to-arc-orc...

https://www.youtube.com/watch?v=aUJcYTnPWCg

https://github.com/stisa/nwasm

You can also go an Emscripten route: https://hookrace.net/blog/porting-nes-go-nim/

Re: WASM -- https://github.com/nikki93/ng-public -- Public repo for a game side project I've been working on that does Nim -> C/C++ -> WASM (native desktop also works, iOS probably works (have used the same build system for C++ iOS before) and Android can be made to work). One of the modules involved wraps entt which is a template-heavy C++ library and not many languages can actually wrap with just a cdecl-y ffi layer.

Re: borrow checking: https://nim-lang.org/docs/manual_experimental.html#view-type... It's still pretty early and also IME the mix of arc (which is determinstic) with manually managed memory (esp. through some data structure that manages entity data like entt) has been pretty nice.

Nim is apparently getting support for owned pointers [1]. There's a proposal [2]. The proposal PR has since been closed, but it's apparently still being worked on.

[1] https://nim-lang.org/araq/ownedrefs.html

[2] https://github.com/nim-lang/RFCs/issues/144