The cloud-instance Linux clients we usually hear about are headless servers, which again gets into use case. Desktop-as-a-Service may still less popular than display attached right to a local computer, which you need in some form anyway even if you use Cloud PC or Linux equivalent.
Advantages have been listed, and there’s no comment yet on use case, e.g. self-service restore without bothering you becomes far easier if the user of the cloud desktop can do their own ones.
EDIT:
Point-in-time restore for Windows 365 Business explains what you get if you go that way, and is reminscent of my comment about Linux VPS providers. I don’t know if a full restore fits your use.
Where the data is also matters. For example if you rent a small Cloud PC with a small drive, the data might be elsewhere such as OneDrive, and certain OneDrive versions have some recovery capabilities even against ransomware mass destruction (where rollback to point in time is good).
Of course, although any file-oriented ones that do source scanning of distant cloud device will be slowed by that. There are some very expensive commercial solutions such as Veeam with agent architecture, but your scale sounds like you want something aimed at not-enormous deployment.
Solutions aimed at small business sizes exist, e.g. for managed service providers (are you one?).
One open source backup that (I think) does remote agent is urbackup, but then it needs backup, sort of like your local NAS needs remote backup. Direct-to-cloud-destination avoids an extra hop.