I have a single domain - mysite.com

I want to run an on-prem bind server that resolves all of my on-prem servers / services, but I ALSO want to use the same domain in google's cloud dns to resolve some stuff i'm dorking with up there on a free trial, just trying to learn the ecosystem.

so, on-prem would have things like ubiquiti.mysite.com, or proxmox.mysite.com as single sites. Then in the cloud I would have mysite.com as just a static web page, and nextcloud.mysite.com, etc.

I'm using ephemeral IPs on google, so what I want to happen is instead of adding dns entries for everything in my bind server, I want it to forward the request to google dns if it can't resolve it on-prem, even if it's in the zone that is configured.

does that make sense? (not asking if it's best practice, asking if its possible)

I've looked at split DNS, but it doesn't seem that that's what I want.