Build debian packages for arm64

I’ve got a C++ project. I’ve already setup builds for amd64 for different debian and Ubuntu distros. How would I do this to provide packages for raspberry pi3 or other arm64/armhf platforms?

Can this be done on
If not: Are there other services, that provide arm64 build environments?

I’ve not tested those in any way, but here are gitlab-runners for ARM platform:

If installed on your PI you may register the runner to gitlab (either .com or CE) and build for the ARM platform via the CI pipeline.

This works for armhf 32bit, unfortunately there are no official arm64 64bit packages for gitlab-runner