I have a views search page in D8 where I'm I have exposed filters that are shown in blocks. I'm also using search facet blocks. What I want in the sidebar is the exposed filter text search field, followed by the facets, and then an exposed filter for selecting a date range.
I've seen a few places mention you can create a duplicate of the views page keeping the same path and have one set of filters in one views block and others in an additional views block. I think this was for D7 because I can't make it work in D8. Basically they replace the url arguments when one or the other is submitted instead of combining them like they normally would do.
What I've currently done is shown the exposed filter block twice and using CSS (display: none) to aria-hidden="true" hide the redundant exposed filters from screens and assistive technology.
It gets flagged though when I used WAVE to test its accessibility since there are duplicative form labels. It's also, imho, a nasty hack and I'd rather do it the right way if possible.
Is there a right or better way?