To devs, io means input/output. Almost every language comes with an IO base library. It’s also a bit like 1 0 as in binary. It’s very relevant to devs. OTOH .is is good by there is plenty of nice 2 character tlds out there you can make words with

I would be concerned with usage rules; many ccTLDs state that you must have a business presence in the country where the TLD is registered. Googling around for a few minutes, I was not able to get a clear answer, though it's presumably in the lengthy ToS of ISNIC.

Reading through the is domain rules [0] (which are in addition to the ToS), it does seem like the only requirement most people will have to watch out for is that there website must comply with Icelandic law, which, considering their more complicated understanding and implementation of GDPR (some parts have been rejected), may be quite a task.

[0] https://www.isnic.is/en/domain/rules

Just forget .io

http://www.thedarksideof.io/