I always love to see these projects attempting to create an Open-source parametric CAD tool, but I think they will never get the the level of functionality and stability required. The fundamental issue for all of them is the lack of a robust open source "parametric CAD kernel", these the the central core that understands BREP and implements the geometric operations.
The most widely used kernel is OpenCascade, the kernel used by FreeCad. However it is outdated, unstable and limited in significant ways with no realistic future prospects. It is unfortunately the limiting factor of FreeCads functionality and prevents any serious use of it.
The most widely used commercial kernel is Parasolid, used in many packages including SolidWorks, OnSpace, and NX.
What I would love to see is Siemens adopting a model similar to some of the game engines (Unreal and Unity) where it's free up until a revenue limit. Opening up Parasolid for "free" open source and small commercial operations would be both brilliant for society but also for Siemens, it would only result in a growth in the use of Parasolid and increased revenue.
The first one, Truck[1] seems to have a company behind it, Ricos Ltd, that look like they to know what they're doing[2]. The tweet shows their product using functionality from Truck (the frontend is not OSS AFAIK).
Fornjot is an ambitious project IMHO. Their kernel is in a separate crate[3].
As for OSS code that could be a good base to either use (or port to something like Rust) for someone to write their own kernel is Ayam [4], the oldest OSS 3D NURBS modeler that is still being developed.
[1] https://github.com/ricosjp/truck
[2] https://twitter.com/RICOS_ltd/status/1550390552482693120