Yeah, I am pretty close to that, the pihole to unbound, unbound DoT to cloudflare. What I am doing at this point is bypassing the DNS to ISP, but as I stated in my response above, not yet blocking everything on the net from using the regular stuff. Just feasibility testing at the moment.
Love the dual setup for DNS. I set my primary to this and my secondary to just cloudflare at them moment for when I bork my primary DNS will fidgeting with it, haha.