Personally I'm using as a provider "solnet.ch" (I'm their customer since a very long time and so far I'm very happy with them - it's a small provider headquartered in the canton Solothurn, but my connection originates from the canton Zurich), and so far it doesn't seem that they'll offer IPv6, so this matches your statement.
On the other hand, if I remember correctly, I think (not sure and I cannot check this now) that I did have to modify my DNS configuration of my email server related to IPv6 when my parents changed from Swisscom to Sunrise (in 2020 or 2019 - my mother uses my email-server and the IPv6-entries weren't configured correctly) => can it be that Sunrise is using IPv6 as well, at least partially?
I might be wrong, especially regarding what you mean with "natively" (maybe you mean that customers get "only" an IPv6-address, the access to the IPv4-network being fully relayed at the ISP-level?).