I’ve never done iOS dev, but is there a way for me to load my own dev app onto my phone from Xcode or something. I’d like to not let 3rd parties get access to my texts.
Yes, but unless you pay $99/year, you'll need to reinstall the app every 7 days.
If I pay for a dev account, then I won’t have to reinstall it?
As far as I know, if you have a dev account, apps installed yourself will be valid for a year, instead of 7 days. I've never done it myself though, so this is just based on what I've read.