Yes, we could collect all the posts with links to the songs using the hashtag and put them in a Cryptpad or Nextcloud public accessible file, like you said.
If there are too many suggestions, it might be helpful to use a script to scan the feed later, but that depends on how many people participate.
But instead of people writing their suggestions in a shared file, we thought they could just post on Mastodon using a hashtag, like people do with the hastag #MusicWomenWednesday, to share recommendations. The advantage of posting here is that people can let comments or boost, which is also a way to "promote" European artists. :)