You can see all about Grassroots for Europe (GfE) here: https://grassrootsforeurope.org/.  It was started by local groups as a counterweight that the periphery could provide to the centre, represented by the European Movement.  As such, there is a good symbiosis between those two organisations and multiple memberships are frequent for groups and individuals. As well as providing a weekly online forum, and frequent newsletters, GfE organises webinars. One outstanding achievement, following a post-Brexit conference, was the creation and continued running of the Grassroots Round Table which allows many different organisations to discuss topics of common interest and attempt some coordination of their activities.  This page is not quite up to date, but gives a good idea of the Round Table, which is still hard at work.