Safari provides an option to add a webpage as a shortcut on the home screen. Android should have something similar. 
I can open https://timechaincalendar.com/en in my phone browser (Duck duck go). It looks like a web page. How to turn in into full screen app?
Discussion
I used the option "Add to home screen" in duck duck go and it created a shortcut on the home screen, which opens duck duck go with the page. Not a real app!
I tried with Chrome. It has option "Install app", which works as expected! Thank you!!!
Yep, native browsers normally have this option. Chrome on iOS doesn’t for this very reason probably.
Glad it worked.