(I'm unsure where this should go so I'll put it here.)
I'm Bernard one of the founders of Open Source Design (and a happy user of Joplin for bout 6 months). We're a collective of UX designers who advocate for UX design contributions to, and work on, F/OSS projects.
We organise UX design tracks at conferences - every year at FOSDEM conference (in Brussels, Belguim), and we've also organised them for ApacheCon Europe and FOSS Backstage.
We invite open source software projects and companies to submit a talk about design in free and open source software. If the community votes for the talk we invite them to speak.
Would someone from Joplin be interested in speaking at our Open Source Design track in February 2022?
Right now we're waiting for confirmation from FOSDEM organisers that our devroom has been accepted. Once we have confirmation we'd welcome someone to submit a talk for the devroom.
Over the past 6 years we've had a lot of interesting talks about design in free and open source software. You can see some examples at the online archives - from last year all the way back to 2015.