I'd love to see something like this for Solidworks, but think you're in for a boatload of trouble there. OpenCASCADE is less capable than Parasolid, and a true Rust-based parametric geometry kernel capable of boolean joins, fillets, etc. needed for anything resembling a modern feature set is wickedly difficult (that's one of the reasons why everyone licenses existing ones and don't try to roll their own).
Don't let that discourage you, though! A fast, local, fully-featured 3D parametric CAD program that takes advantage of modern hardware parallelism that can be extended/scripted is just basically one of the holy grails of software and even exploratory efforts might uncover some great paths forward to making that a reality!
Don't let that discourage you, though! A fast, local, fully-featured 3D parametric CAD program that takes advantage of modern hardware parallelism that can be extended/scripted is just basically one of the holy grails of software and even exploratory efforts might uncover some great paths forward to making that a reality!