TL, DR: It looks like those with the patience to compile a kernel+drivers can probably manage using Denverton boards [1]. I was blocked by no available drivers last year but hope to come back to my build project in the fall.
NB: I'm just a casual tinkerer not an expert.
Back story: Last summer when Intel shipped Denverton, QAT (which offloads crypto) apparently got a substantial speed boost and I saw claims that 10GbE IPSec should be possible. Denverton boards vary but some top end ones apparently ship with 4 10GbE NICs [2].
Back then the issue was that the QAT drivers weren't ready, so I put my project on hold. Today I see Intel has apparently shipped Linux and FreeBSD drivers. [3] Would of course be nice to see these drivers land upstream but no idea what the licensing story is like here.
[1] https://www.servethehome.com/intel-atom-c3000-series-launch-...
[2] https://www.servethehome.com/supermicro-a2sdi-h-tp4f-review/