It’s not true that IPv4 is unobtainable, you can e.g. apply to become a RIPE member & LIR to obtain a /22 subnet of addresses. The cost is in the several 1000 €’s per year if I remember correctly. You can equally well try to reach out to an existing LIR and rent addresses from them of course. Not sure if that corresponds to your definition of “owning” IP addresses but as a LIR you can theoretically hold on to the addresses indefinitely.
More info: https://www.ripe.net/participate/member-support/become-a-mem...