Any citizen can do a citizens arrest for a felony. What citizens cannot do is arrest or detain for misdemeanors, nor serve traffic tickets or warrants.
When I read the ROEs from the TX ARNGs provost marshal and JAG, THEN we will know if TX is serious.
I think a citizen’s arrest of a federal agent for “dereliction of duty” would be a good start.
I'm not worried about "potentially fatal encounters with illegals"...I'm thinking more along the lines of a bad precedent being set. Namely, the same argument for deploying troops along the border of TX can (and would, do you trust Gov. 'Moonbeam' Brown?) be used by other state governors to deploy troops against protesters at "Send the @$#@$@ illegals home" rallies.
You're absolutely correct on the ROE. That'll tell the tale.
Truly, we're living in interesting times.