Vultr allows floating IPs for IPv4 and IPv6, but Digital Ocean only has floating IPv4. Vultr will start a machine with a floating v4, but you have to add a floating v6 address (giving you two v6 addresses). Digital Ocean does the same thing with v4 (giving you two v4 addresses). They both have different network adapter names, so you've got to configure those per provider as well.
Terraform and my own thing help in easing the transition if you ever need to move, but modifications will still have to be made.
