Mitchell Hashimoto, Hashicorps longest serving IC, has been working on his own terminal emulator as a side project: https://mitchellh.com/ghostty . It's been interesting to read through his logs and see how it develops along with the gnarly bugs he gets to work through.
That's just my bad attempt at a joke. "Longest serving code writer" may be more accurate, but IC gets lumped in as that so frequently and he publicly took that title back on. This is getting less funny the more I try to explain it..