How to use external C++ libraries in lambda expressions?

I need to calculate checksum using some standard algorithm. There are C++ libraries that can do that.

How can I find out if such library is available within ESP Home platform, or if it is not, how can I add some library to be used within lambda expression?

Does this cover it? Generic Custom Component — ESPHome

You mean I have to create custom component to be able to calculate hash on a string?

I am not entirely sure to be honest. You could try just putting the library into your esphome directory, and including it in your yaml.

I don’t know either. But maybe the stuff they mention about libraries in this section might help.

“It is also possible to use specific versions, or to fetch libraries from a file or git repository.”