If you're asking about using Tesla Superchargers, there is no investment other than the time required to download the Tesla app and then finding one of the very few Superchargers equipped with Tesla's "Magic Dock" adapter. Note that Consumer Reports reports: "Charging a non-Tesla with a Supercharger is currently one of the most expensive fast charging options per kilowatt-hour (kWh)." You can buy a $60 adapter to use a Level 2 Tesla Destination Charger, if you can find one of those EVSEs and you have lots of time to burn. That's not a big investment.
If you are asking about buying a supercharger adapter to charge your Kia, the superchargers and adapters won't be available until sometime in 2024. So you are going to have to wait until it happens. Even with the adapter, you may run into issues with the voltage mismatch between the superchargers and your Kia. Also the short cables on the superchargers may be an issue too. Note that some folks aren't happy with the use of adapters and believe they are a safety issue for regular high voltage/current use. If I was planning to use Tesla's superchargers on a regular basis, I would want a vehicle that has the North American Standard receptacle built in. So far Kia has said no to that due to voltage mismatch. Also the superchargers around here are going to variable pricing. So you will pay through the nose if you charge during peak hours and get a bargain rate if you charge in the wee morning hours.
