Hi SunnyInToronto
Re: Conspicuous alert for ring/silent switch preferred by those who ① don’t find focus as accessible?
Seems iPhone 15 Pro and iPhone 15 Pro Max do have a visible Action button in place of the Ring/Silent switch.
For iPhone: Apple support provides some tips in the online article: Silence iPhone - Apple Support
ie: not all sounds are muted in Silent mode.
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Re: " ... problem is I often forget to reset to normal mode. Is there better alert such as periodic low audible?"
Seems there is only this one:
Temporarily silence calls, alerts, and notifications
Open Control Center, tap Focus, then tap Do Not Disturb.
(See Turn on or schedule a Focus on iPhone.
eg: says: To choose an ending point for the Focus, tap 
, select an option (such as “For 1 hour” or “Until I leave this location”), then tap again.)
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IMHO : Only solutions in sight
Two taps for Do Not Disturb
Two taps to set and forget ... nothing to do to turn it back on after a time or location change
Else ... use (or wait for) visible action button on newer iPhone.
or
perhaps others have useful suggestions ?
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Re: ② Screen time concern : Wallpaper is lessor alternative IMHO due to
1. Phone is often in my pocket.
2, screen time priority not only for battery drain but also eye health.
Unsure what your concern is here: If you are concerned about iPhone activating when in a pocket:
If Raise to Wake is on you can turn it off: Go to Settings > Display & Brightness.
or see if you can place iPhone face down in the pocket instead.
More info: Use Raise to Wake on your iPhone - Apple Support
All the best :-)
