Do you use ReasonML on the backend as well? Or just something like ReasonReact? I've been interested in Reason and still wondering the best way to work it into my NodeJS/React/Typescript stack.

I am not parent comment's author, but I use TS on the backend and I did look into ReasonML. I love most of Reason's syntax and FP in general, but unfortunately, reason/bucklescript ecosystem just isn't mature enough for a serious project. I'd recommend against using it unless you are in some megacorp and you can afford to build general-purpose tooling.