My perception of Oracle is that they'll do very underhanded, even criminal, acts to extract money from entities who have at one time used their software.
Happily, I have enough alternatives to VirtualBox to let me avoid that risk.
If you want to provision a server as a VM host, Proxmox free version is pretty good but you have to manually update it.
Maybe some little tweaks here and there to target specific ones in the vagrantfile, but otherwise I’ve found it to be largely a non issue to have different hypervisors, so long as you have a base box that supports all the ones you want to use (which is part of why my company builds base boxes - to have something reliable for client projects - either used as is, or where appropriate building on top of our box setup process to make customised boxes)
I'm not sure if there's a better option today, and/or for different host/guest combos.