For the sake of keeping it straightforward and within character limits, I kept the original post simple.
Yeah, it depends on integrations.
Generally you can follow accounts on other Fediverse platforms from microblogging services like Mastodon. However, some features may require a native account.
For example, if you watch PeerTube videos then your Mastodon account is enough, but if you want to upload you will need an actual PeerTube account.