People I trust to understand Constitutional Law (those who teach it & practice it) say that S3 of 14A requires a "finding" & that "finding" must be a criminal conviction. In other words, Trump MUST be convicted in a criminal court before S3 of 14A could be used.
S3 is short & easy to read & it makes no mention of a "finding" requirement, & even if the need for a finding is required (I can understand how it might be implied due to due process requirements) it doesn't specify if that finding must be a criminal conviction, or perhaps an act of Congress passed by majority vote of both chambers.
This seems like it may be a case where we could try it & let the courts sort it out, with the possibility that SCOTUS would clarify what's required to invoke S3 of 14A penalties.
The 14th Amendment:
[link:https://www.law.cornell.edu/constitution/amendmentxiv|]