I finally got my Friendica account to see the Tarot bot on gotosocial. To start with, search did not like trying to find the tarotbot account (probably because Friendica uses a slightly different format for user names). Then when I did find it, Friendica would only follow the RSS feed of the bot, not the activitypub bits. But I was able to reblog a Tarotbot GTS post on my Mastodon account, which let my Friendica account see the tarotbot post as activitypub instead of RSS.

Anyway it works now, the end.