No, I think if you’re using the nextcloud all in one image, then the management image connects to the docker socket and deploys nextcloud using that. The you could be able to update nextcloud via the web ui.
https://github.com/nextcloud/all-in-one?tab=readme-ov-file#how-to-update-the-containers
Amazon has a “refurbished” program, where you can find lots of cheap thin clients and smaller form factor desktop machines.
However, the refurbished computers often have their SSD/HDD replaced with a crappy one that is unreliable, so I would recommend assuming that you assume that you will need to buy storage in addition to that.
But, overall I really like Amazon Refurbished because you get a better quality guarantee (warranty/returns), but a cheaper price.