Arc, TBCNY's browser for macOS and Windows uses Swift [1] [2].

Their newer Dia browser which is meant to be cross-platform also uses Swift.

[1]: https://speakinginswift.substack.com/p/swift-tooling-windows...

[2]: "How we're building the Arc Browser Windows app with Swift" -- https://www.youtube.com/watch?v=Xa_fNuaSE_I