Pace 500.3 accessories

I’m looking for accessories for a Pace 500.3 step through. Looking for: 1. Bottle/cup holder. Because it’s a step through there’s no top bar to attach to so it would have to somehow wrap around the battery and wouldn’t be permanent (I guess) 2. Saddlebags. I have the Aventon rear rack attached. Why didn’t they include a spring clamp in it like I used to have on my bike when I was a kid? The rack is useless without bungee cords. 🙄 Anyway, I’ll need some kind of saddlebags to carry anything substantial. 3. Seats. I know that bike seats are not necessarily the most comfortable places to park your tush but I’d like something that doesn’t kill my rump. After 20 miles on poorly maintained bike trails my tail bone feels bruised and my “twig and berries” have been taking a beating.

Am I limited to what Aventon sells or are there makers you recommend that are compatible?

Thanks.