The market is changing and hence anything can happen, most airdrops are already worthless with only few having value, but with the positive market now, who knows there could be a change in things, therefore I understand you. Back to your question, I think most bounty managers also handles or have an airdrop channel which they also used for projects which is hosting a bounty as well as airdrop, and the one that comes in mind is bounty detective. I think there is another with the name "airdrop alert" you can check it on telegram. Well, since airdrops are pretty worthless now, endeavour to go for the right ones.