I think the challenging thing with this is that it's a niche market that is easily handled well enough by small local players if they want to, but I think it'd be a touch sales process to make it scale by aggregating fulfillment at scale and get people to think about this as something they want. From my perspective, in terms of the tech side it'd be "easy", and finding people to do the work shouldn't be that hard, but the sales process is something I'd be wildly uncomfortable with.

I suspect this is one of those things where you need a lot higher margin than you think to offset really high customer acquisition costs. You need to find people who believe they'll visit often, probably will visit less than they think, yet won't care too much about putting down 2k/year+ for the convenience, partly aspirationally.

A quick search shows storage units in Nice to stick with that, easily comes down to <8 euro month per cubic metre, btw., so it's certainly doable to make something like this into a relatively cheap subscription. The effort is in finding customers + signing up local partners to deliver.