Sure, I can access Contacts within Proton Mail, but that's a lot of taps. And when I want to add or edit an entry I can not do so within the app -- I'm shunted out to a web interface.

My first choice: A full-featured Proton Calendar app for Android and iOS.
My second choice: Ability to fully edit Contacts from within the Proton Mail app.

Why?

I have been using Proton's services for quite some time, starting with the free version. I have used/use various applications offered by different technology companies, such as Google and Microsoft. So, to be perfectly honest, I ask again, “Why?” Why request various applications without plausible circumstances? Google, Microsoft, Samsung, and even government apps are developing various apps without any express need. And in the case of Samsung, it has done, or I believe it still does, the issue of having multiple files and folders in its file managers, leaving an extreme mess.

In other words, I am a passionate advocate and supporter of digital security and personal privacy, and I have no complaints against the services of the Swiss company Proton. However, I consider myself a digital minimalist, as I see no need to request multiple applications.

However, I believe that if I wanted to request new applications, I would request (if it is in Proton's interest) an authenticator application, I would not link Proton Docs to Proton Drive, but would create an application, Standard Notes, which I believe I would modernize or transform into a Proton notes application, and finally, I believe I would create Proton search, or I would partner with other search engines and, if I wanted to, I would acquire these search engines.

All of this is my personal opinion.

Now with Android 16 there is a contact storage settings that could be set

Please go ahead with this feature

Please add a mobile app for contacts that functions as well as the Google contacts app.

This idea seems similar to an older one (with the most votes @2025-03-09):
https://protonmail.uservoice.com/forums/284483-proton-mail/suggestions/45241207-proton-contacts-mobile-app

And then there is also this other one that is similar:
https://protonmail.uservoice.com/forums/945460-general-ideas/suggestions/48248672-contact-application

This seems to be duplicated https://protonmail.uservoice.com/forums/945460-general-ideas/suggestions/48248672-contact-application

Something that can be selected as the default contacts app, offers sync, and basic contact fields, notes, and tagging.

In general something to replace Google contacts with more privacy, but also the integrations you would expect.