One of our 2 cats, brothers, is looking exactly a Maine Coon, esp. with the lighter colored ruff, thick hair
( but under it he is still not very heavy yet).
now I recognized his lil meows, which are quiet compared to other cats, like his brother who Yowls when he wants something.

From what I have read, they are fully mature until age 4. Wonder if he will develop ear tufts?

They don’t all have ear tufts but they usually have lots of hair in the ears. Riley, the rescue non-purebred, could have definitely passed but for his petite size. They all chirped. They all had great personalities, very loving and smart. 2 of the purebreds and Riley had fur that matted easily and they needed the summer lion cut.

The long hair, neck ruff and fluffy tail for sure. MCs can be any color but pointed (Siamese pattern). I've read a lot about the breed and they occasionally allow a non-pedigreed cat with good MC features to breed with the purebreds so they don't get "overbred" like some dog breeds.
I enjoyed having the "fancy breed" cats but felt guilty about rescue cats needing homes so after Ricky died in 2011 I've only had rescues, like our current boys (shorthairs) Charlie and Andy.

On edit: they don't have to be really large but many are. My only female MC was on the petite side, way smaller than her brother.

Got these 2 last Oct. at 5 weeks old, from a friend who was feeding their feral mother, so I have no idea the parentage, but really did not expect to run into that breed way down here the boonies in Ala. we are really off the beaten track.

His brother is a b/w tuxedo cat with enormously long whiskers. They are 14 months now and suddenly becoming BIG.

Look at the cats in that video.

Could be a Norwegian Forest (my sister has one).

fine and feels like angora fur?

Had to get one trimmed a couple weeks ago for that reason.

Ricky, one of my purebreds, was a brown tabby with a slightly coarser coat than the others and he rarely got mats. The other 3 had very fine fur and seemed to "break out" on mats and needed lion cuts annually.

They're amazing cats.