I created a sharepoint list, which has two datetime fields allowing the user to choose a time and a date. At first glance, everything appears fine when I generate the power app.
Unfortunately, however, the time is always 2 hours ahead (for times) in the Power app vs. the Sharepoint list. Everything seems to be set to my local timezone, and no other settings are jumping out to indicate other options.
This issue is making Powerapps unusable IMO.
I agree that the way dates and datetimes are handled in PowerApps is awful. There has been plenty of feedback on this, but nothing has yet been done. I live in hope.
In the meanwhile I work around by saving dates in yyyy-mm-dd text format, and you can do the same adding time if you need it.