Yeah it shows a tiny little balloon-tip style thing over the hamburger menu.

I was going to say it's not a big deal but I quite distinctly remember it being the entire reason I switched to Vivaldi instead of Chrome. Full extension store compatibility with none of the nagging, and all the other cool shit it does is just a bonus at this point.

It does. You can pay 5 bucks to get a dev account on the play store and then upload your extension there (unlisted if you want), and install it from there, and you won't get the nag popup