Recently I was told that in Catalina (and beyond) I wouldn't be able to have a script launched from a LaunchAgent plist, as LaunchAgents have to be signed app packages now or something?

I was using a LaunchAgent because Jamf Pro's own functionality to run scripts at login seemed to be unreliable or delayed at the time - is this still the case?

With those things in mind, is there a good free option that still allows me to run some kind of script at login without needing to become an Apple Developer and write a whole app for it?