Hello everybody! I decide to take frontity to redo my WP web site in to React.
So I try to make main page editable from WP admin (and also want to make same another pages), and use html2react processor for display content.
My issue is next:
I want to add slider on WP side, and decide to use slider as gutenslider (really doesn’t matter which to use). And it doesn’t render, so what ways to render slider from WP side (wp is latest version).
And second question. Is there in frontity is all ready SSR from React side? For example, if I make full custom page from React side, is it content will be recognize by serach robots ?
Welcome to the Frontity community. Great to hear that you’ve decided to use Frontity to redo your website. 
You should be able to use Gutenslider so long as it adds the content to the WP REST API. However, you will probably need to write your own logic in Frontity in order to get the slider to change.
Gutenslider is probably using JavaScript in order to change the slides, so it’s probably worth diving into the source code to find out how they’re doing it. As Gutenslider is open source you can reuse or adapt their code.
To answer your second question, yes one of the key features of Frontity is that it’s an isomorphic application with SSR so your SEO is unharmed - see here and here for more info.