You are mentioning that an experiment with nextcloud has failed? I cannot find any evidence regarding that, even more I see it highly used among governments and municipalities in the EU.
Tangentially, although there's been sporadic setbacks, as Limux[1] in 2017, there are new commitments to linux[2] that I hope will lead the way, at least in Europe.
I can tell that a few years ago a couple of NRW libraries used a SuSE variant in kiosk mode, apparently not everyone found that great, as some of the ones I regularly visit now have Windows in kiosk mode, with the usual set of Office, Adobe and other packages.
I’m aware of a party in Germany which, at some levels, uses Nextcloud to great success so I could imagine them pushing for it in their fraction. No idea why that wouldn’t work though given that they have tons of experience
