Hmmm, that could get confusing. Mastodon does not appear to understand lemmys sublemmy format of !sublemmy@lemmy.domain but if you format it with the "@" it works. As an example !monero@lemmy.ml does nothing while @monero does. However, regular lemmy users use the "@" as well, so to mastodon a sublemmy and a standard user are exactly the same.
@Hamartiogonic @lemillionsocks same, though i hace to look at "all" to do it and i have never once opened r/all on reddit. I bet that will no longer be needed in time