Make sure whatever you set up has a conveniet bulk download option. Else it might border on predatory practice if the only option for your client to save their copies locally is to download every one of them individually.
Apart from that I don’t see any issues why you cpuldn’t supplement your income by offering hosti g services to your clients, as long as you can guarantee their data is secure and confidential and it isn’t too much of a hassle for you to manage that.
Truenas server in my basement made from old hardware people were throwing away and a bunch of drives in a configuration where I can lose two of them and still recover, so I can have piece of mind not running the most top tier reliable newly bought drives.
Add an easy to set up wireguard vpn paired with duckdns as a dyndns provider makes my personal ‘cloud’ storage solution with a minimal risk of anyone unauthorized accessing my data.
In addition to solid hardware don’t underestimate psychological effects. Use of proper contrast through lighting, harmonious and contrasting well balanced colors set up in situ and the tweaked to perfection in post all will contribute to perceived sharpness just s much as using good glass will
Darktable has a library management built in. Could help with automatically sortimg your photos by date into labeled folders. From there you can just start working on your backlog amd make sure to tag and maybe rate any new incoming photos in a timely manner so as not to add to that nacklog of work.