There actually is a method of adding a wheel and being able to reasonably keep ABS. But it does require a new monitor to read the rotation speed of the two and instantly produce an average for a new signal feed. If one wheel of the pair locks up, you send a half speed signal to the OEM ABS computer and it will still read it as "ACTIVATE ABS". For a standard rear trike, the driveshaft mechanically does that average and I think is what at least one manufacturer does to keep ABS. Having the front as the pair will require the new monitor to average the two.
For me considering a trike in the (hopefully distant) future, my interest is Tilt Motor Works with tilt lock. Losing the linked brakes is not that significant with me. Losing ABS is more significant, but loss of ABS better include the loss of linked brakes too. I do not want the brake peddle to be responsible for a front wheel lock-up, nor do I want the hand brake lever to be responsible for a rear lock-up. Either case requires the total release of the brakes to get the affected wheel rolling again without ABS doing that for you. That is bad news for the reason you are hitting the brakes to begin with.