Sorry I missed this, though this would probably make for an interesting Ask HN question by itself in terms of what the current best practices are. But for shear simplicity I'd probably start by looking at 1st party solutions: Apple's Configurator 2 and Google's Android Device Manager. macOS was also updated to support mobileconfig files a while back, so you can make profiles to deploy there too. That is probably about as minimal as it gets: simple applications that generate a file which can be distributed over USB or via messages or email and such to set up a range of functions. Setting up a server and command line generation of your own files and such (some tools like the Algo VPN maker will make deployable profiles themselves for ease of use) can be fun, but for a handful of your own private devices with relatively static settings it can be overkill too. A profile may be plenty good enough, and can also just plain save a bit of time by making it easier to load up a bunch of email accounts for example. Also, for the Apple case specifically, they perhaps unsurprisingly expose a lot less functionality in the native mass market user aimed UI then their devices actually support. iOS devices have native support for S/MIME certs for example, but you need to a profile to add them.
Anyway I'd suggest trying those first before digging into server setups or cloud offerings or the like.
