Hello. I have found the wix subpage, where I read, that I can use node js server. Is it true and I just can deploy my node.js app to the wix as I can do with other providers?
If you just click on Explore Documentation then you will be able to see the pages that tell you more about it and how to use the Wix Package Manager with any node.js that has been approved and can be used.
Thanks for an answer. I looked at the docs before, but I was a bit unlucky - the first page that I tried didn’t exist ( https://www.wix.com/corvid/forum/wix-tips-and-updates/example-using-the-places-api-from-google-maps-services ) and generally I couldn’t and still can’t find straightforward answer to my question (If I can deploy plain full node.js app to wix and eventually how). Maybe I am missing something but I can’t see article on deploying app to node.js server.
So let’s say I have developed an app using express.js, exposing rest endpoints, that I can without problems and modifications run on most services that provide node.js server. Can I deploy it on wix without modifications? I will appreciate direct answer (yes / no) 
Yes you can add node.js to your website, providing that they have been approved by Wix.
https://support.wix.com/en/article/corvid-managing-external-code-libraries-with-the-package-manager