MicrosoftThe PnP vertical web part support just fine to have verticals on the same page. And you can configure result type matching in the result web part to work for content per vertical.
And, the idea for PnP Modern Search in my mind is not to replace the Microsoft Search result pages, but rather give you an opportunity to create search based portals or content roll up. You can of course disagree 🙂 With the upcoming features to allow configuration of the verticals and using adaptive cards to render items you should be able to cover more use-cases.
I would not recommend anyone to build a full search center based on the SharePoint classic features today, but you can. I haven't recommended this for many years, so not marketing talking 🙂 And this is why. With Microsoft Search being available from more and more applications (header searchbox), covering more and more data, and having a unified look and feel across clients - wouldn't you confuse your users by having one experience in SharePoint only with a subset of the content (over time)? And how can you control where they search from?
That said, your workaround is to hide the OOB search box, and roll your own search box/use the PnP one per page - this way you get as many pages as you want, but they will contain the SP header. There are no plans to allow multiple no-header pages on a site outside of this scenario for obvious reasons.
A question, can you share scenarios where your users cannot solve their search ask using the current oob search experience?
