It seems that Warp.dev also might be using GPUI - at least that was my impression based on their website [0] (I might be wrong though). Which is a good think that another popular project is consuming such crate.
[0]
"... we partnered with Nathan Sobo, co-founder of the Atom text editor, who had already started building a Rust UI framework that was loosely inspired by Flutter"
I think they started out using GPUI, but might have diverged. They mention flutter and GPUI v1 was Flutter inspired. GPUI v2 which is what's not released to the public isn't Flutter inspired anymore.
[0] "... we partnered with Nathan Sobo, co-founder of the Atom text editor, who had already started building a Rust UI framework that was loosely inspired by Flutter"
https://www.warp.dev/blog/how-warp-works