Power switch again, but without mechanical switch

I've been browsing the posts related to powering alpha/delta remotely using attached switches. However, all the discussed switches were mechanical ones (counting a relais as mechanical switch).

Is there an option to connect the LP SW pin directly to a digital pin of the Arduino? Like: Put Arduino pin into high-impedance mode => SW not pressed, drive the Arduino pin to low => SW pressed.

If decoupling is required, how about some optocoupler logic? Using a relay seems so 20-century-ish.

Thanks.