I’m part of the Austrian Fairphoners and we regularly attend events related to sustainability - so not necessarily your primary target. In 2019 I will bring a demo Fairphone running /e/ to every event (it currently looks like this) and promote /e/ as one great option for the Fairphone (along with FP (Open) OS, Lineage OS, Sailfish & Ubuntu).
At some of these events we have a booth/tent where many hundreds of people will come by a day, but these will probably not be very attractive to you.
What might be more interesting is the annual #efct (European Fairphoners Community Trip). This is a week where very active Fairphone community members meet - for the past 3 years in Amsterdam to visit the Fairphone office - in 2019 maybe it will be in Stuttgart DE instead.
Besides sightseeing and getting to know each-other we usually have two days reserved for workshops and short keynotes.
The attendance is not very high, but you could introduce the ideas behind /e/ to about 30 very active FP community members who cold become multipliers and promote /e/ at events and meetups all over Europe like I will do in Vienna/Austria.
A soon as it’s fixed I’ll let you know the date and location of the #efct19 if you are interested. Another option would be you just share some material for a keynote or a short video with me and I’ll introduce /e/ to the others myself - or find someone else to do it, because tbh I’m not very keen on talking publicly.
Maybe some community material to share for local word-spreading would be a good idea anyway? Print-outs, keynotes, videos, etc…
Also if you ever attend an event near Vienna AT I’d love to come by.