4 pane comic of dolan on the left and spooderman on the right
pane 1 (dolan): cum join opensurce cummunity!
pane 2 (spooderman): shure! how joyn?
pane 3 (dolan): Here discord! (with discord logo)
pane 4 (spooderman with tears in eyes): y u do dis?
Please, not phpBB. Whatever the merits of PHP as a language are now, phpBB came from a time when it was exhibit #1 of why the language was terrible.
Adding a community on a Lemmy instance is fine. Far less admin work on your part, too. Encourage your users to donate to the people who do run the instance.