We are making really good progress on this and will have a cross-platform prototype in the next month or so. See the Github issues for Linux[1] and Windows[2]

[1] https://github.com/withfig/fig/issues/34

[2] https://github.com/withfig/fig/issues/35

Sounds like they are actively working on adding support for Windows and Linux; https://github.com/withfig/autocomplete#does-fig-work-on-win...