After a quick research I found that issue 291 (where support for mypy plugins) was "close as not planned". So I created this fork that has a complete plugin system that compiles plugins on WASM and runs them with Wasmtime.
The main idea is to allow plugin authors to use the crate `ty_plugin_protocol` to easily compose plugins, by implementing a protocol that communicates with ty with versioned JSON requests and declarative patches.
I also crated the first plugin for this system: Django-ty, which aims to have 100% coverage of the features that the popular Django-stubs offers.
Feedback is welcome!