The best advice I saw on resigning is, only resign a position if you could win it 100% of the time against the best player in the world with 30 seconds.
Is it courteous to resign in a lost position?

It all depends on the situation, the position, the time control, the opponent.
Also, I believe if you don't resign in some positions you can get a warning from chess.com for stalling?
It's not stalling if you keep playing moves

At higher rated levels, about after 1700, when you are down a piece or more you should just resign. Don't waste you and your opponent's time by playing up a completely lost position.
However, if your opponent has a nice checkmate, you should let them play it instead of resigning and not allowing them to get the chance. That is good sportsmanship.

At higher rated levels, about after 1700, when you are down a piece or more you should just resign. Don't waste you and your opponent's time by playing up a completely lost position.
However, if your opponent has a nice checkmate, you should let them play it instead of resigning and not allowing them to get the chance. That is good sportsmanship.
Even when I'm a piece down in rapid, I still save (or my opponents throw) about 25% of those positions (and vice versa). If it's easy (like K+4P vs K+P), then I'll resign. If I can see some way that I could blunder this with the colors reversed, I keep playing.

The best advice I saw on resigning is, only resign a position if you could win it 100% of the time against the best player in the world with 30 seconds.
I've used a similar rule of thumb, although I specified "Stockfish" rather than the best player in the world, and I didn't include the 30-second rule.
But it also depends on the quality of you opponent. If you've blundered yourself into a dead lost position against a very low level player, they will sometimes blunder badly enough to let you back into the game.

You should resign unless you have some stalemate chance, but otherwise definitely resign
I always do that
like I took 20 seconds to find this one and it worked.
https://www.chess.com/game/live/84450200589

You should resign unless you have some stalemate chance, but otherwise definitely resign
I always do that
like I took 20 seconds to find this one and it worked.
hilarious your opponent wanted to make 5 queens but it was stalemate! it was rapid too, but they got so excited they pre-moved!

The best advice I saw on resigning is, only resign a position if you could win it 100% of the time against the best player in the world with 30 seconds.
I've used a similar rule of thumb, although I specified "Stockfish" rather than the best player in the world, and I didn't include the 30-second rule.
But it also depends on the quality of you opponent. If you've blundered yourself into a dead lost position against a very low level player, they will sometimes blunder badly enough to let you back into the game.
Exactly, if I’m down a queen against someone a lot lower rated than me, then I also probably wouldn’t resign there too
It all depends on the situation, the position, the time control, the opponent.
Also, I believe if you don't resign in some positions you can get a warning from chess.com for stalling?