Hey Freddy,
The GUI version of the deployment center (twdeployerGUI.exe), as you’ve already found out, does have a requirement to be run as an administrator and this is unlikely to change in the future.
The CLI version (twdeployer.exe) does not have this requirement. So the only suggestion I can give you for now is to create a script with the CLI version that these users can run to perform their upgrade.
The “twdeployer app auto” command checks some things to determine if it needs to be an install or upgrade etc. so that is probably your best option.
Please check the output of “twdeployer app auto --help” if you need help with putting together your script.
This is merely a suggestion on the side but if this works well enough you might want to consider setting up some CI/CD environment around it so these users can eventually just press a button to do the upgrade etc.