With completely wireless earbuds, the rule is: when the battery fails, they have to be disposed of. Not so with the Fairbuds, that allow you to replace batteries in just a few seconds. Combined with a repairable design, the earbuds should therefore have an extremely long lifetime.
You can buy a USB-C splitter or replace your current dongle with one that gives you the exact ports you want.
For example, the Belkin Rockstar is USB-C to USB-C+3.5mm jack. It’s $40 but there are a ton of cheaper options - JSAUX has a few for $15 or so on Amazon, and there are other no-name branded versions out there for around $10ish.