Yesterday I did a talk at the #PHX365 meeting on the high level differences between classic and modern sites in SharePoint 2019 on prem, and how you can use SharePoint Framework to extend SharePoint 2019 both on prem and SharePoint Online. Thank you to all who attended and for the great questions and feedback!
I’m including the slide deck from the presentation for those who wanted to review later. The last slide in the deck includes a bunch of helpful links around SharePoint Framework. Enjoy!