I reached out to Mark-Kashman and Naomi Moneypenny about the lack of enterprise search in SharePoint. I continue to be impressed and excited by the improvements in Search elsewhere, which exacerbates the frustration with the downgraded Modern experience in the otherwise outstanding work in SharePoint.
The advice is that it's on the https://www.microsoft.com/en-us/microsoft-365/roadmap?rtc=2&filters=&searchterms=Customize%2Csearch%2Cresults%2Cfor%2Cyour%2Corganization and that it was announced at https://myignite.techcommunity.microsoft.com/sessions/65663#ignite-html-anchor:
I don't see metadata filtering or the other basics referenced there at all. It is interesting that easily half the question at Ignite were about the absence of enterprise features in SharePoint, so it's not just Wicus van den Berg and I that are wanting it.
It would be good to have an update on the actual plan for Modern SharePoint Search; ideally by way of a blog and roadmap item.