It's short, cute and easy!
In reality, I'm only the first of those
In true weaboo fashion, the answer is anime.
From Pokemon Sun and Moon, to be exact. Y'know the grass starter, the owl guy? Rowlet, his name was.
His Japanese name is Mokurou. The Moku part means 'tree' (Fitting, since, he's the grass starter).
Then the Rou bit, hmm, think of it as a suffix to mean 'Child of'.
My previous account was named LoveYaGuys, and since I had exactly 0 friends, I'd never felt the need to make an online name before.
However, I had thoughtlessly added my IRL relatives to my LoveYaGuys instagram account which hugely limited my cringelord antics.
So I wanted to make a new account, this time I thought I wanted an actual name, and since I was watching Pkmn S&M at the time, I flippantly used moku._.chan as my username, and the rest is history (There's actually nothing else).