If I understand it correctly, the nft and crypto coins you guys get can only be spent inside their testnet and not in the real world right? But, why you seem to be positive about it when the real one that you will get from doing these kind of tasks are their own token which value is also small since they are still starting but you can always hodl it and see if it became huge later on.
There is a risk in doing this because we may be required to connect our wallet and there are projects who are scams which can rob us. This is why the OP is recommending us to use dummy accounts and this includes creating a new crypto wallet only for this purpose.
Yes, all the coins and NFT that you receive in the test network can only be spent in this test network to complete tasks. But the reward at the end of testing is distributed in the main network. It will be possible to talk about the value of the coin that you will receive as an airdrop only after it starts trading on the exchange.
To eliminate all the risks associated with the loss of the contents of your wallet, you need to use a new wallet specially created for this purpose.