Are there differences between ISPs (Swisscom, UPC, …) and their routers/modems when it comes to port-forwarding, IP management and so on?

Does anyone have previous experiences and suggestions, for which ISP I should go?

Edit for update 11.2023: Init7 with the 777.- a year plan has the option to add a 20.-/month extra for a own public, static IPv4. This was too expensive for me, i gave up and went with the cheap Yallo something, which has the whole GC NAT shenanigans. I now hope for better ipv6 support in the comming years… Mostly by the fucking shit mobile shitproviders 😡😡, mobile data by all isps in switzerand has NO ipv6 support