Is anybody aware if it is possible for organisations under 100 users to purchase Enterprise licenses or equivalent? The community edition of Nextcloud is, of course, excellent, however micro and small businesses also want to benefit from early security patches, also need to prove GDPR compliance and also want to use officially-supported Helm charts, just as larger organisations do.
I think the official way is going to one of their partners and resellers, so they provide you with the service and pass you the advantages of a business subscription: Nextcloud partners
I think you’d have to look at the resellers. I don’t know if they provide a service so that you keep your own setup? Check out the website if you find the details, if you are not sure and have further question, I’d contact the official nextcloud channels since we are only the community and cannot give you more details other than reading the websites ourselves.
Hey @PronouncedDelight, welcome to the Nextcloud community 
The community forum is a community of volunteer enthusiasts helping and supporting fellow enthusiasts. The community has a huge knowledge base and there are some very clued up folks who gladly share their knowledge and expertise in the spirit of open source.
While Nextcloud is open source and the sky is the limit as far as user numbers and scale are concerned, there is only one “edition”, thus there are no early security patches etc. for subscribers. The number of users is not relevant for subscription and only a recommendation, so you can subscribe if you please, Get a quote - Nextcloud. Your best option is to talk to the folks at Nextcloud GmbH. They’re certainly very helpful and inclusive and no one is going to shake their heads and turn you away.
Boundaries and limits are fluent and there’s plenty room for interpretation. As a rule of thumb you could say, from ~100 users you’re looking at a corporate instance and from ~500 users you’re looking at an enterprise solution and you’d be best looked after by the engineers, consultants and professional support at Nextcloud or affiliate partners.
You’ll find community documentation and deployment recommendations here;
You’ll have access to concise expert documentation upon subscription here;