For compatibility bike seats are pretty much standardized and will fit any seatpost. Seatposts come in several diameters and you can use any seatpost that is the same diameter as your bike takes. For Lectric bikes the seatpost diameter is 31.6mm. The comfort package is $99. You can buy a Cloud 9 Cruiser seat for $37 and a DJC Bike Suspension Seatpost post for $30 both on Amazon. The seatpost is the same type and the Cloud 9 seat is one of the more popular aftermarket seats people choose. This seatpost will work. Just choose the 31.6mm size. https://www.amazon.com/DJC-Suspension-Seatpost-Absorber-Lightweight/dp/B08BGB8G1V?th=1&psc=1
although I got the more expensive SunTour seatpost. https://www.amazon.com/Suntour-SP12-NCX-Mountain-Suspension-Seatpost/dp/B00BXPMJBY/?th=1&psc=1 Also, I don't know about in this reddit group but in the facebook group there are a lot of messages regarding the spring in the comfort seat breaking. It did on mine too. I bought the Cloud 9 Cruiser seat and my wife has a YLG seat.

Don't waste you $$ on a cheap suspension seat post, it's basically riding on a spring, There's a much better option but it's about $80, that and a decent basic comfort seat I chose based on good amazon ratings both made a nice improvement in my hardtail.