Speaking ahead of the Belgian Grand Prix, Russell said: "I think Nyck is a fantastic driver. He is a Formula 2 champion, he is a Formula E champion.
"He has definitely got the speed, he has got the charisma and the right attitude to be an F1 driver.
"Unfortunately, Formula 1 only has 20 drivers and for a great driver to come in a great driver has to leave so it is not quite as simple as that.
"He deserves to be here but let's see if he gets the opportunity of the opportunity arises for himself. Unfortunately, there isn't enough space for everybody."
Russell would choose Hamilton as team-mate
Should Russell be confirmed as a Mercedes driver for 2022, he will be given the opportunity to go head-to-head with seven-time champion Lewis Hamilton, an opportunity he is relishing.
"As any driver, they want to go against the best and Lewis is probably the greatest of all time so you want to put yourself against and see how you fare," he explained.
"It would be probably an honour for anybody to get that opportunity. It is all hypothetical at the moment.
"It is the same as I said three years ago, if I could choose to race against anybody as my team-mate, Lewis would be the one."