I've looked into doing this as well. I watched a bunch of DIY YT videos and one guy out in east Texas had a set up where he had 3 5000 gallon poly cisterns up to catch rainwater.
During the drought last summer or the one prior the ground dried out, shifted and cracked. Causing his underground PVC pipes to crack and leak the 15000 gallons of water he had collected
He switched from PVC to PEX or something similar so that it would be flexible.
My father had issues with his sprinkler system pipes leaking last summer, I assume it's because of the ground drying out since the system isn't that old but I could be wrong.
Something to think about.
I'm all for doing it and I think there is value in every drop you are able to collect and save but it seems like to me if you're going the above ground catchment route you would want one or two big enough to make it worth your while.
What I mean is that are you going to have a tank that fills up after a half inch rainfall or will you be able to hold water if you get a good few days of rain.
Good luck. I'll be following.
Also I think @troph did this on their new house but I could be wrong