Thanks for the quick response!
We are in a similar situation and plan to continue using v0.18.0 for our MCU use cases for now.
Exploring the Relax flow on the side. Have made some progress with a static build of the runtime and updating the C source backend to generate code that uses the TVM global registry (vs. the module registry) to handle calls to vm builtins such as vm.builtin.alloc_tensor. Need to figure out how to auto generate the main wrapper that calls __vmtir__main and handle weights/params in the C backend.