Update, 8th January 2022:
So we have looked in to this. It's far more complex than first suspected -- EAC has two versions. Non-EOS and EOS (Epic Online Services). Most games historically use Non-EOS EAC. It's the one Vermintide 2 uses as well. Epic only added Proton support for the EOS version of EAC. Therefor in order to implement proton support for Vermintide 2, a huge amount of reworking of the EAC implementation would be required, which may also require all players to authenticate with Epic Online Services as well -- perhaps even logging in to the Epic environment (to be confirmed, however).
So the "just a few clicks" statement made in the original announcement wasn't entirely accurate, and would only apply to titles using the EOS version of EAC, which simply hasn't been many games aside from either pretty new ones, and likely predominantly Epic exclusive titles.
We are still looking at what is or isn't going to be possible, but it's not as easy as it was made out to be -- far from it in fact.
There may be other solutions or workarounds, but ripping out the old EAC and rewriting everything to implement "NuEAC" and potentially asking our entire playerbase to connect through and sign through EOS for an honestly tiny market share that was (and would remain) unsupported from the get go might be a deal breaker.
Time will tell.
We are aware Easy Anti-Cheat have newly introduced support for Linux via Wine/Proton.
Currently, Vermintide 2 will not work for Linux users via Wine/Proton as it has to be manually enabled on our end. Whilst we wish it could be done in a couple of clicks, realistically we require dedicated resource, planning and QA to ensure it runs as seamlessly as possible.
The conversation has been initiated internally, and we will update this article once the next steps have been established.
Please be aware that whilst we will do our best to make it viable, it is unlikely that we will support Linux in an official capacity due to a lack of resource. Therefore, once live, we will not be addressing issues in Vermintide 2 that are isolated to Linux, and customer support will remain limited to Windows, Xbox and PlayStation only.