I’ve settled on a dialect of C++ for systems programming after using C for a long time. It’s mostly C-like and I disable exceptions, RTTI, etc. but I do use templates, overloads, methods, lambdas, etc.

I have my own object system with constructor methods that all return a status code so you don’t need exceptions, my own stdlib for containers, buffered I/O, networking, hashing, math, threading, async, etc.

C++ gives you all the features to effectively build your own language, and you can use first class tooling since C++ is widely supported. LLMs also make it much easier to build out and test an entire stdlib on your own.