You can write your glue nano-service in c/c++ if you want, it’s just that: glue. It doesn’t matter as long as you don’t need to change the original services which also can be written in whatever you want. Ruby, Python, JS just work out of the box with aws lambda and you don’t really have to maintain them or any sort of build infra so it allows for very little maintenance or upkeep cost. You don’t really test these glue lambdas either.
You didn’t read what I wrote at all.