Note that since recently some cheaper providers (especially UPC and its sub brands) have switched to CGNAT, which does not support port fowarding as your modem does not get its own IP assigned. I have been always happy with iWay, Init7 and Green.ch. they are only slightly more expensive (except Init7) but their service is awesome and super nerdy :)
askswitzerland
Question about Switzerland? Get your answer here!
I know about Swisscom, UPC (Sunrise Cable), Sunrise. As far as i know, you can do port-forwarding on all of them. But mostly it is just plain port-forwarding and not much more. Really depends on what you like to do.
My target is to have a remote connection over the internet onto my home server, to access jellyfin and maybe my NAS as well
Should basically be possible with all of them. It could be that some ports are blocked by the provider, but this shouldn't be an issue.
I know that upc supports port forwarding, a public ip however costs additionally.
Maybe you're no longer looking for an answer, but I heard good things about init7, that they are self hosted friendly.
Their website has a "nerd mode" which gives additional technical details, useful for selfhosters. They have few options but all of them are high bandwidth and unlimited, it seems. Perhaps something to fit your needs?