What I did was to download the arm64 debs of docker and dpkg install them in dependeciy-order, since any automated script grabbed armhf on both vero4 and pi3, doing it my way is not really a good solution, since there is no autoupdate, but it works.
Check out the getdocker script, then use the url in there to download the docker-debs, I had it all documented but lost the textfile, before i could move it to my “knowledge db”.
Edit:
here is some screenshots of portainer, showing env and an image running arm64 docker: