I can set up Proxmox VE as hyper visor, some container for each DBs, load balancer in front and some app in about an hour max from scratch, with good testing and some bells and whistles, and here I really do not want to brag or the like, as such operations are not my job to do at all, I only know because I do that occasionally for some tests and for some private infra I just maintain out of interest - so I really want to say, if some operation-dork can do that, the engineer you hired should be able to do it at least as quick.
But yes you're right in the general point, upfront setup and frequent maintenance is naturally something you need to price in. I just think that if you have that many different parts with complex coupling to induce such a huge maintenance effort required to keep your product running, the cloud offer may not really be your salvation and just delay the fall while costing all the more.
