Hi!
If you don’t need a particular feature of Veeam Backup & Replication, I’d suggest you look at Veeam Backup for Microsoft Azure instead.
I say this purely because I consider VBfMA more “evergreen” in that additional Azure native protection features are added to this product instead of into VBR.
With VBR you’d be limited to deploying Veeam Agents to your VMs and currently you’d have to provision traditional VM disks to store your backup (VBR/Veeam Agent can’t backup to object storage directly, YET!), whereas VBfMA can backup directly to object storage, it can also handle snapshotting your VMs in addition to backups.
In either scenario I recommend you create a separate tenant for your Veeam backup platform vs the production/workload Azure environment, it’s better for isolation, I’d also go one step further and use a separate billing method for this too, so if you have a billing issue that takes all your VMs offline, you could recover them to your isolated tenant for a DR as one example. Primarily however it’s to ensure a compromise of your production Azure tenant, doesn’t bring the recoverability of your backups into question.
As for Veeam Backup for Microsoft 365, yep that’s fully supported, I’m paranoid and would recommend having a backup of M365 data outside of Microsoft as there was a lot of talk a decade ago about Microsoft utilising Azure for some of the M365 services, but there’s no real detail on overlap, at least I’d want to use a separate geo-location!