Do look also at the ready made ones, which have been designed especially for folks with various levels of dementia/Alzheimer
I linked before to uk societies' shops - there should be usa equivalents
and searching amazon for "dementia clock" will provide ideas, even if there's no ideal product on sale
Back to fire tablets- you can access remotely using ADP debugger. Once you have enabled developer mode you can connect via LAN and push apps / files. I have done that with fire tv so same methods shoudl work with fire tablet.
To ask the experts on how to do clever stuff with tablets go here
https://forum.xda-developers.com/
I asked google for
dementia clock app and found this.
you can add google store and apps easily to fire tablet
https://play.google.com/store/apps/d...dayclock&hl=en
A clock that shows the time of day to help people with dementia. Can be run as a 'daydream' screensaver to keep it visible at all times.