There are at least 3 popular type connectors for battery charging ports. The most common battery voltages are 36 Volt (v) and 48v. However, 52v and 60v are growing in popularity. I considered building a solar charger for our outbuilding at work, which is used to house bicycles which are ridden to work.
In a controlled environment like mine, I don't have to worry about equipment being stolen for the "copper wire" in them. They same might not be true of a public park. Then the question becomes "charging current". Some bigger packs are quite happy at being charged at 5 amps, smaller packs may need a lighter 2 amp charge. All my chargers at home are currently 3 amp power packs. Thus far at home, I have standardized on 48v Lithium Ion batteries. This makes charging easy. But keep in mind there are those who have 48v LifPO4 batteries, which require a different kind of charger than Lithium Ion batteries.
The Wired Freedom bikes are calling my name recently, and they require a 60v
ev charging station. Only the future can tell.
Smaug's suggestion of "Bring Your Own Charger (BYOC) sounds like the most sensible idea.