are there any initiatives to work wordpress as microservices?

No, without going into too much ranting, the wordpress core philosophy is based on user experience and API stability, this kind of restructuring is impossible without “breaking some eggs” so I don’t imagine core wordpress to go that direction in any time soon.

In addition, it doesn’t make much sense for anything smaller than google/amazon/facebook (ok, I am exaggerating somewhat). The cost in performance will be staggering for the site hosted on a shared host and even for small VPS it will be just cost with not much benefit.

OTOH there is an effort to provide json based rest API, so at least the UI can be run as a totally separate system. Maybe other parts will follow…. but it is hard to imagine right now what other parts of the wordpress core might be a standalone subsystem.