When hosting a server IPv6 doesn't make a huge difference beyond your logs will probably be a bit more accurate, people behind CGNAT where an ISP has multiple customers sharing a block of IPv4 will show up with their actual IPv6 address. They'll maybe also find it slightly quicker because they're not being funnelled through NAT gateways but realistically not enough to notice.

From the user side IPv6 is great for me. My ISP is using CGNAT and would bill me ten pounds a month for a static IPv4 address but I automatically get a vast block of IPv6. I'm using that block to allow me to VPN back home when out and about, and if I wanted to I could also host services from devices on my home network without needing any NAT nonsense, I can just open access to the relevant device on the router. (Because this is a world where not everywhere supports IPv6 yet if I'm on an IPv4 only network the VPN endpoint is a dedicated server I rent which forwards the relevant port back to my home router over IPv6)

So your isp is rinsing you for the cost of a an IPv4 address. £10 a month will pay for a whole /24 in 3 years.

Chances are they also skimping on other areas including over subscription. Choose a better isp if you want a better service.

Your “just open traffic to internal host 1 on your firewall is the same no matter if it has nat or not, unless you are using a non stateful firewall? Or perhaps your configuration layer splits the two for reasons.

Thank you for the advice. By any chance, have you worked with Ruby before? I remember seeing your username back when Ruby was popular and I first started learning it in university