and you need ATP to fly it at work? If not, then it's straightforward quick FAA comm/ifr. If non-US national, only needing the TSA 'clearance' for twin rating, too. As you say, the hours flown would easily add up to those required for ATP in current conditions, till end of July passing ATP written. The single complex vs twin time is up to you/your budget and bearing in mind the initial twin commercial needs plenty twin dual training, 5hrs iFR in twin, the qualifying XC, night, etc.
Get interpretation on(whether) needing cpl and ir in class/category or not and heli ATP would be enough. Doing European ratings in your case doesn't make sense obviously due to the European PIC for IR and CPL even though you'd not have to do much IR training in aircraft. So using the ICAO licence/ratings clause is irrelevant to you.