I don't know the answer, but I hope (although I'm not sanguine about it) the answer is zero.
That said, if DHS is prioritizing hiring such folks for ICE/CBP (as a paramilitary force bent on domination of the US controlled only by Trump and his minions), we're going to have serious problems getting the current administration to vacate on 20 January 2029, especially since these folks have a budget larger than most military forces around the world.
Is that alarmist? I don't know. Then again, so many unprecedented, authoritarian and outright illegal things have been done by the current administration.
As such, it wouldn't surprise me to see right-wing militia thugs on the ICE/CBP payroll. I hope I'm wrong. I fear I'm not.
[0] https://www.splcenter.org/resources/extremist-files/?meta_ex...
Edit: Maybe I'm paranoid, but so many of this administration's actions seem to come right out of the fascist/authoritarian playbook (cf. https://archive.ph/xbm1E although there are many other expositions of this as well).