I would never directly punt any kind of linksite on Tiktok, always put Instagram on Tiktok and on your Instagram your linksite, I use my personal site on Insta so not sure if Fanberry is save, but I do think it isnt any less save then Beacons or Linktree.
Yes, you can safely post on Instagram (as your main link, in your bio). We use Fanberry as our main link for Cam101 on Insta as well, so go make a beautiful fanberry page and rock your links in all your socials!