Based on this reply, I get the distinct impression that you know a LOT more about networking than your original ELI5 post lets on, and almost certainly more about the subject than I. I work in tech, but not with networking specifically; most of my knowledge is from way too many years and dollars spent on homelabbing.

One of my internet connections is a DSL connection; by default, they provide a single IPv4 address. My DSL modem has an option to enable IPv6 tunneling through IPv4, but I was never able to get it to work, and customer support was completely clueless. I suspect this isn't something their network supports and they're just counting on their users not caring. My other connection is over satellite (Starlink), and as far as I am aware, they're only providing a single IPv6 connection, not a block of addresses.

To make things easy, I've just blocked IPv6 at my firewall, and I use policy-based routing on my PFsense box to send traffic to either connection depending on latency/bandwidth requirements (Streaming goes to satellite, VoIP goes to DSL, etc). I know that IPv6 has improvements beyond just "more addresses," but at this point I can't really justify enabling it on my network. It would only be used internally, and I just don't see any tangible benefit.