I'm interested in any new successful startups going full IPV6 from the beginning. Once we cross that bridge, where your internal IPV4 knowledge is equivalent to token ring knowledge, there's nothing else to watch.

One interesting development is the Matter standard for controlling smart home devices is v6 only. Every lightbulb, switch, sensor etc gets a v6 address and can be individually communicated to without having a manufacturers hub translating in the middle.

While definitely not a startup, the National Archives made https://clintonwhitehouse1.archives.gov/ and https://clintonwhitehouse2.archives.gov/ IPv6-only.

While I don't think a couple administration's website archives are enough to drive adoption, one could imagine there might be some government resources that might.

Sadly browsers don't seem to warn users that they couldn't connect because of the lack of IPv6 (and doing so would be difficult for IPv6-only DNS servers), so it just looks like a regular connection failure.

Github still refuses to switch on support for ipv6 traffic for some reason, so you can't interact with github then

Relatedly: wouldn't there be many applications for which ipv4 isn't needed?

For example, Walmart has electronic eink shelf tags they can update remotely. Each one needs a unique address. I wouldn't think it needs ipv4. It doesn't have to connect to the SpaceJam website.

I would think that as time goes by, the number of these new devices would swamp the number of old ones that need ipv4. v4 would still be around and might even seem important to the fogies using web browsers on laptops...meanwhile the street lamp has five ipv6 addresses and no ipv4 ones.

It would be a strange and unnecessary risk to take for a startup in my opinion.

Exclusively IPv6 without any transitional mechanisms would be difficult to succeed with.

However, there are network upstarts like Jio (India) which made huge v6 investments from day one which use 464xlat for subscribers to access v4-only resources.