FreeForm: Adding attributes to the honeypot field
It looks like this isn't something that's currently possible. The code that generated the honeypot field isn't able to be extended vendor/solspace/craft-freeform/src/Services/HoneypotService.php::240 

I ended up doing some js magic, like this:

if(this.formHoneypotName) {
    let stickyFingers = form.target.querySelector('#' + this.formHoneypotName)
    params.append(this.formHoneypotName, stickyFingers.value ? stickyFingers.value : '')
}