Simple clock displays UTC and Local Time on android phone
This is just an html page that uses JavaScript to display the UTC time along with Local Time and date.
That's it. (well actually, the latest also shows solar info from N0NBH's HamQSL.com AND there's a ten-minute alarm to remind you about Station ID AND now the Brite/Dim button for the graphic pops you up to the top of the screen. But besides that, it's just a clock.)
It scales sorta-kinda, so you can put it on a tablet (untested) or laptop or turn the phone over to landscape if you need larger numbers.
There's an APK to install on an android, and I pulled the HTML out if you want to just copy to a folder and look at it in a browser. The SPK file is also there, but I don't know what it's good for.
I run it on a Pixel 3A, rooted, with LineageOS, using AccA (appstore) for charging management so I can keep it on a charging stand 24/7 without it blowing up.
I also use a very cool app called KinScreen (appstore) to keep the screen on for extended periods while I'm messing with the radios. Recommended!