There is currently a bug in the firmware of up-to-date Tizen 4 TVs that prevents developers from installing applications. The widget is transfered to the TV, but then the TV firmware screws up the destination path and the install fails. Hopefully this will be fixed soon.
h--ps://developer.samsung.com/forum/thread/install-via-tizen-cli-fails/201/354129
There is a bug in the device manager of Tizen Studio 2.5 for both Windows and Linux that fails when trying to install an app onto any TV. A dialog immediately appears saying ... "org.tizen.sdlib.exception.SdbCommandRejectedException: closed". To install apps onto a Tizen 3 or older Tizen 4 TV, you need to use the command line "tizen install -t [model] -n [widget name].wgt -- [folder]". The command line installer will say that the install has failed, but just ignore that message, it probably succeeded.
The Tizen Studio 2.5 certificate manager will generate a Tizen certificate, but if for any reason you need a Samsung certificate, use the Linux version of Tizen Studio, the Windows version bugs out trying to connect to the Samsung website.
I hope this post saves others from having to waste time discovering these problems themselves.
Cheers, Rex