I like the experience of reading in Muse.app on the iPad. It's a nested whiteboarding thing, but also can act as a PDF reader. (It'll let you pull out chunks of the PDF and put it on your canvas with a link back into your document, if that fits your flow.) I often read on my phone, so this is not an option for me.
Apple Notes and Muse slow down with a lot of ink. For taking a page full of notes I'm using Notability.
I've heard good things about GoodReader, but haven't played with it in years.
https://apps.apple.com/us/app/pdf-expert-editor-reader/id743...
MacOS and iPad: DevonThink paid app with sync via P2P, WebDAV or cloud services.
Optional local mirror/sync of web pages and PDFs, with full text search.
It seems to work in MacOS and iOS; an iCloud account is probably required.