I'm waiting since 2021 for this feature. Patiently :-) My 2 cents: Start by supporting one dictionary format, e.g. Stardict ... Make it so that found definitions can be included in Anki cards. If people have several dictionaries for the same language let them decide which definition to use on the Anki card. Have a look at Yomitan, Hoshi Reader or Jidoujisho to see how it could look like ...
The Android app already allows users to open third-party dictionary apps with a single tap or using services list in translation panel. Its name is Share with an external app