In the US and I use my own personal modem and router. Renting their equipment is optional.

Yes CGNAT is used quite a lot, but consider 95% of customers don't care what their public address is and that "saves" the carrier address space.

We are the 5% that do care and if you call your ISP they likely have an option to exclude you from cgn and get an actual public IP.

What ISP do you have and what country are you in? I have Comcast in the US and do not have this issue even though they are a big and shitty ISP (I even use their modem, but I do have my own router which I HIGHLY suggest).

i repeatedly petitioned our landlord (once a year) to allow an alternative isp to hook up to the building, and he eventually was so pissed from my requests that he threatened to press charges against me personally if the electrical box were ever opened

I bought my own cable modem and router for less than what my ISP would charge to rent them to me. They control nothing on my end.

Apologies if you've answered this elsewhere but I'm assuming there's a reason you haven't bought your own router?

It gets worse - because ISPs are choosing NATs over IPv6,

Yes, because they're mostly pieces of shit, technically inept and unable to properly deploy IPv6 at a large scale.

Either way IPv6 doesn't fix everything as you'll still need a real IPv4 to access a large part of the internet or some translation (MAP-T/MAP-E). Even if your ISP provided dual stack with a real public IPv6 + CGNAT / MAP-T IPv4 it would still be annoying as you wouldn't be able to do port forwarding on the IPv4 and won't be able to access your self-hosted services from a LOT of networks that are IPv4 only.

There are two versions of MAP – translated (MAP-T) and encapsulated (MAP-E). In MAP-E IPv4 traffic is encapsulated into IPv6 using a v6 header before it is sent over the v6 network. At the network operator’s boundary router, the IPv6 header is then stripped, and the IPv4 traffic is forwarded to the v4 Internet. In MAP-T, the IPv4 packet header is mapped to the IPv6 header and back. The difference between the two options is evident in their names. MAP-E uses IPv6 to encapsulate and de-encapsulate IPv4 traffic, whereas MAP-T uses NAT64 to translate IPv4 to IPv6 and back.

And this is why I'm unlikely to change isp. I have a /29 ipv4 block and /48 ipv6 block. No extra charge. Grandfathered features from over a decade ago.

Yep, the US reserved most of the ipv4 for them so they have no need for CGNAT, I had to change my ISP to host a terraria server for my friends because of it, but if you don't live in a big city you have no options.

I read that you can say to your ISP that you need port forwarding to use a remote camera system and they will make an exception for you, but I just switched since I even got a better speed deal.

I had a fun little issue a while back where my isp replaced our fiber modem to one that didn't allow for port forwarding. The settings were missing but when I set up dmz host on that to allow our equipment to work again, I noticed it was behind some nat in their system. I found out I could call them to get functionality restored for a fee, but instead I plugged in the old box and still keep an external ip with port forwarding enabled and no nat. To be honest the old one has been a lot less stubborn as it doesn't drop every 10th packet on the network. I switched back about 6 months ago, and I've not had any issues, so we'll see when they call demanding me to plug in the new one. Their explanation for switching systems was that their old one wasn't powerful enough for gigabit speeds, even though both have interfaces for gigabit sfp. After some testing, the old one was more capable and stable at those speeds. I assume they wanted to switch systems due to some licensing thing, or to get more money from the .5% of people who care about these features.

I'd advice to look into ipv6 tunnels and try to get that working. Abandon ipv4 when your isp refuses to ipv6.

You can't get your own router?

In my country, the ISP rents you a modem and router. I told them I had my own modem and router during setup and my monthly cost is slightly less than their advertised price.

I am fortunate that my ISP gives me a routable address, but it is still only dynamic and may change a couple times a year. I would have to pay for a commercial plan if I want a static IP. Some other local ISPs use carrier grade NAT, but you can still request a publicly routable static IP with a business plan. Maybe you can ask your ISP for that?

This is primarily geographic

If you're trying to self-host http service, you can use cloudflare tunnels.

In my country we just buy a router and ask the ISP to set the modem/router in bridge mode

Cheapest vps plus "sshuttle" may work, host everything on your home server but have dedicated ip of your vps

Standard IPv4 NAT or CGNAT?

Are you using their modem AND router? Or just their modem? If it's a modem router combo, can you place it in bridge/passthrough mode?

Even if it's CGNAT and no bridge mode, their are solutions available.

Are you looking to host private services like NextCloud? Or public services like a website?