Hi Angelo, good question and glad you asked… yes, yes, and yes!
In the case of the listed enterprise nextcloud-solid hosters, the ones listed here are a subset of the parent list of enterprise Nextcloud hosters. I contacted all of them last summer on behalf of a customer who was interested in getting a Solid-Nextcloud server hosted for production use, and each of the ones in this shorter list have said “Yes, we can support that app as part of a managed installation”. The others either said “no, that’s not a thing we offer”, or they didn’t respond.
Regarding security audits, I know the NGI program of the European Union sponsored a security audit of Solid-Nextcloud, which was carried out by Radically Open Security (who are awesome for several reasons by the way).
Regarding SLAs and security audit of GraphMetrix TrinPod, I actually don’t know the specifics but I have asked @gibsonf1 and will update here when I can give you more details.
From personal communication with @wouteraj I know that Digita use.id has both SLAs and independent security audit.
Regarding SLAs and security audit of Inrupt ESS, there is ample information on their website; this product page mentions terms like “production-grade”, “advanced security”, “enterprise ready”, and “up to 24/7 support for operators and developers with a commercial license for ESS”, this page mentions " Inrupt’s premium SLAs" also Bruce Schneier has linked his name to Inrupt, so although I couldn’t find any specific information about independent security audits that have been carried out on ESS, I trust he takes care that they have their security audits in order too.
Regarding the “Open Source” claim, you can see which hosting providers have published their code on GitHub and which ones haven’t.
This list is tailored for organisations / companies / governments who actually want to store user data or offer WebID’s for their employees / members / users / citizens / etc.
So that is what makes this list different from the list of demo servers that is more aimed at people who want to try Solid out or to develop Solid apps against a hosted pod server, and from the list of self-hosting options which is mainly aimed at enthousiasts, researchers/developers and hobbyists.
Having said that, we didn’t check or QA these claims in anyway, we just echo here what these providers tell us or what they say on their websites. This list of Solid Pod Hosters for Enterprise is provided just for information, to the best of our knowledge, and without implying any endorsement. Any additions and corrections anyone may have are very welcome, details of how to contribute are in the introductory paragraph.
PS: Looking forward to seeing you F2F at the Solid Symposium in a few weeks!