From your experience, do you check domain name availability before naming a company? It looks to me like this is becoming less important...
There's many companies that either use alternative TLD's like; example.app or example.shop
Or prepend "get" or append "app" to the name to obtain the dot com TLD.
I also think that SEO and search engines make the actual domain names less important now right?
The cost of advertising is the long-term tax you pay for poor short-term decision making when naming your product or service.
What most people don't realize is that it's the "sound" of the name that's most important, not the way it looks on a logo or in a domain name.
The reason for this is the part of the brain's working memory called the phonological loop that gets excited by short repetitive rhyming sounds and rehearses them repeatedly, which is why you sometimes can't get a song or tune out of your head. This function results in repetitive and rhyming names being more readily committed to long-term memory, thus making good names not just memorable but unforgettable.
All the the best names are alliterative and rhyming, and I'd argue that Coca-Cola is the best name ever conceived so far.
"So does the available domain matter?"
Yes, but nowhere near as much as the name itself.
It's very possible to come up with original great sounding unique names that position you well in the marketplace, it just takes time and a lot of patience.