Since while I was doing research I stumbled accross this thread, but it didn't bring me to the result I wanted. So I decided to register here to point out my approach to aquire the need of fetching posts with multiple post types.

One thing is that the restAPI just does not accept multiple post type natively. I assume thats why getEntityRecords also does not provide that capability. 

1st) I registered a new RestAPI Endpoint to get the ability to query multiple post types when using it:

    //PHP
    add_action( 'rest_post_query', function( $args, $request ){
		$post_types = $request->get_param( 'type' );
		if( ! empty( $post_types ) ){
			if( is_string( $post_types ) ){
				// filtering posttypes, seperated with comma into an array, ignoring square brackets
				$post_types = explode( ',', str_replace( array( '[', ']') , '', $post_types ) );
				foreach ( $post_types as $key => $post_type ){
					$object =  get_post_type_object( $post_type );
					if( ! $object || ! $object->show_in_rest   ){
						unset( $post_types[ $key ] );
					}
				}
			}
			$args[ 'post_type' ] = $post_types;
		} else {
			// fallback: no type defined, return post as default
			$args[ 'post_type' ] = 'post';
		}
		return $args;
	}, 10, 2 );


Check your new API endpoint easily by calling it with your browser

    https://*yoururl.com*/wp-json/wp/v2/posts?per_page=10&categories=0&type=posts,page


I don't use the Gutenberg function getEntityRecords anymore to fetch posts. I choose that way performance wise to avoid multiple calls of getEntityRecords. 

2nd) In my Gutenberg block I created a hook to call:

    export default function useFetchPosts( url ) {
		const [data, setData] = useState( null );
		useEffect(() => {
			async function loadData() {
				const response = await fetch( url );
				if(! response.ok ) {
					return false;
				}
				const posts = await response.json();
				setData(posts);
			}
			loadData();
		}, [url]);
		return data;
	}

3rd) to get the posts I just call it like this inside my edit block:

    // parsedCategories and
    // parsedPostTypes  have to set and parsed by you before ofcourse ;)
    const numberposts = 10;
    const postFields = '&_fields=id,author,link,title,_links';
    const posts = useFetchPosts( 'https://'+window.location.host+'/wp-json/wp/v2/posts?per_page='+numberposts+'&categories='+parsedCategories+'&_embed=author&type='+parsedPostTypes+'&orderby=date&order=desc'+postFields );

Check out the restAPI reference for available args and parms:
https://developer.wordpress.org/rest-api/using-the-rest-api/global-parameters/

Cheers