I've never messed with containers because digging yourself out of the thermal hole of starting with a metal box still doesn't sound worth it.
I think the cost to retrofit an otherwise sound but unwanted container is less than the cost to purchase a used one. That is orders of magnitude lower than the cost to erect "standard" solutions to the housing problem.
(i like this dream, but it just isn't practical)
Making the above worse, even though containers are worth more in Asia, and containers of grain are worth a lot: to ship owners they get paid more for the Asia to US trip than the return trip, a ship that leaves the US unloaded (taking on ballast while unloading) and rushes back to Asia makes more money at the end of the year than a ship that waits around in LA to be reloaded with containers.
Maybe if the containers themselves were autonomous and mobile, and could optimize their own value… there’s a Black Mirror episode somewhere in that.