I think I have managed to figure it out. These are the changes I had to make:
Removed the .dev custom domains configured in Pages and replaced then with the equivalent URL on the .net domain.
Changed the Bulk Redirect rules to forward the .pages.dev requests to .net.
Moved all the DNS entries (if any present) on the .dev domain DNS to the .net domain DNS.
Added 2 A records in the DNS for .dev, one where the source is * and the other where the source is @ and I had them point to 192.0.2.1. (For subdomain redirect the * entry is required).
Added a Page Rule in .dev domain to redirect *.davidvarghese.dev/* to https://$1.davidvarghese.net/$2
I also needed to add 2 Bulk Redirects to redirect www. to blog. and finally a Page Redirect for davidvarghese.net to blog.davidvarghese.net but these where configuration which was more specific to my deployment.