I've been daily driving xonsh for a couple of years too. It _sounds_ like a terrible idea for reasons you can't quite put your finger on, but other than a minor annoyance every now and then, it's been great.
I especially like iterating over files as Path objects with the simple syntax
for f in p`.\*\.jpg`:
if f.isdir():
foo = $(echo @(f.absolute()))
Really it's just a souped-up Python interactive shell. When you give it bash commands, it forks to bash. When you give it python it evaluates like a REPL
No new syntax, unless you want to write scripts in xonsh, or mix bash and Python in the same command. There's rarely any reason to. 99/100 times I just write pure bash or pure python
Which I've been using as my daily driver for a few years, and absolutely swear by it.
https://xon.sh