No, do not do it. Polite would be for him to resign.
is it polite to offer a draw when the other player blunders his Queen?

Is this etiquette?
I generally discourage people from taking pity in this way and allowing the draw. I prefer to follow in the words of Mr. Shaibel: "You resign now."

I would say it is not required or etiquette, but it is a nice thing to do depending on the situation.
If your opponent was kicking your butt in a live game, and then made a mouse slip, then it would be kind to give them the draw rather than than take the win. The way ratings work, a one off draw game doesn't really matter after about 10 games.
However, if they weren't going to win or this was a tournament, then I wouldn't accept the draw. Mouseslips and hanging queens are just a thing for online chess.

Also, i have to learn how to win when I have an advantage, without blunder, time out or stalemate !

depends. If you were winning or drawing, I usually just take the win. If I was completely losing, I offer/accept a draw because I didn't deserve the win, just as @Tonya_Harding said.

Is this etiquette?
Possibly if they type to you "mouse slip", sure it's then good sportmanship. But no one will blame you if you take the win instead: it's sports after all, and online, one has to keep control of their mouse like of any other tool they use for the play.
I granted the draw once, for they said "mouse slip", but that's because I was so totally lost and roasted without that blunder: I did not deserve the win. At all.
Choo choo? What’s that noise? It’s your chess engine 😂

It's poor etiquette to offer a draw in a losing position.
It's fine to play on after you blunder. You don't need to resign. But you shouldn't offer a draw either.
Don't make offers which your opponent will never accept.

I would not offer a pity-draw to an opponent who blundered their queen. They need to learn their lesson, not be rewarded for a mistake.

no one is uner any obligation to do anything. if you wish, you may play on for the practice. Ifthe game was either VERY drawish or losing, then i beleive a draw is correct. If it was winning for you, i recomend taking the win. it may also be possible to accep the draw, then play out the winning position against a computer, or your parent or someone else, if you really want the practice

Offering a draw in a won game is an offence to Caissa. It's unwise to offend a dryad.
And it's even more unwise to bow to any idols, pagan gods n godesses.
. .as it is to conflate mythological symbolism with religion.

Atheists claim that religions is all superstitions and mythology, so, there is no reason to say, there is gentle mythology and fun symbolism on one side and evil religions on the other. Or anything such.
Myths can't "contain" anything (or be full of anything). I used to know a homeless guy who claimed to have 100 children. He was a mythomaniac. It doesn't mean that myths contains 100 children. Myth is merely a word naming made up stories and (popular) beliefs founded on the void. Then, myths and mythology, well are two different things.
What utter rubbish, a poor attempt to sound intelligent.
Is this etiquette?