>I’ve also heard your domain reputation is far more important than shared vs. dedicated IP at your ESP of choice.
For me the IP address has been the only significant factor in my email deliverability. I.e., emails sent from my mail server couldn't reach Outlook inboxes or even spam boxes. Straight-up silently rejected every time. If you look at the Outlook.com Smart Network Data Services (SNDS)[0], the terminology used is all about IP. That problem was resolved through a support ticket requesting a kind conditional white-listing.
That's been my experience so far, from the perspective of a low volume, personal email only. YMMV.