I think it’s not a good idea to leave links to Piped instead of YouTube (same for Nitter/Twitter, Libreddit/Reddit, etc.). If you want to avoid YouTube, then just install LibRedirect extension or similar. Piped links are temporary, they’ll break sooner or later, making it difficult for people to get to the website.

Developers don’t have to support Linux natively because Proton does the job very well

Most of subreddit admins and mods are not interested in migrating to somewhere else. A few months after API changes Reddit is still usable and active. Even third party apps are functioning if you apply a patch with your developer token. Also mods don’t want to lose their power.

If you really want to bring more official communities here, you should ask admins who are already interested in open-source or Fediverse. For example, I found that people behind Fossify (a Simple Mobile Tools fork) had created a subreddit. Ask them about Lemmy. It’s FOSS-friendly, there are a lot of fans here, so the chances that they’ll make and promote a Lemmy community are much higher.