I use it as a C++ alternative on Linux. We ported a substantial code base from C++ to Swift last year and it works great. Performance is better in some places, comparable to C++ in others. Productivity is definitely improved over the C++ codebase. We didn’t use rust for this project after evaluating how that migration would impact how it was designed internally, and we decided it wasn’t the right way to go. I think the “swift is only relevant in apple ecosystem” view is inaccurate these days. Swift certainly isn’t the answer to every project, just like rust or any other language isn’t the universal answer to every project. It’s worth considering though if it is appropriate.