How to get full information about "other contacts" using People API?

Background

I work on an app that needs to get information of "other contacts" as they appear on the address book page on "Contacts" website of Google:

The problem

The Contacts API is becoming deprecated, and instead we need to use People API.

For this, I use the Java library (here) which makes it easier to reach the various functions.

Sadly, according to the docs (here), querying the list of items from "other contacts" you will get only up to 3 possible fields:

• emailAddresses
• names
• phoneNumbers

Indeed, when using it, that's what I got. I also got fields of "etag" and "resourceName", but that's it. No photos, no cover photos, no nothing else...

The code to do it is very short (after you set everything up) :

val otherContactsResponse =
    otherContacts.list().setReadMask("emailAddresses,names,phoneNumbers")
        .setPageSize(itemsCountToRequest).setPageToken(nextPageToken).execute()
val result=otherContactsResponse.otherContacts

What I've tried

1. I tried to see if I can query by "reourceName" (example this one), but it seems that "other contacts" are handled differently than normal ones, so this won't work:

result.forEach { personBasic: Person ->
    val test: Person? = peopleService.get(personBasic.resourceName!!)
        .setPersonFields(
            "addresses,ageRanges,birthdays,coverPhotos,emailAddresses,genders,metadata,names,nicknames,occupations,organizations,phoneNumbers,photos,urls")
        .execute()
    Log.d("AppLog", "$test")
}

2. Sadly there is no similar query for "other contacts" part to search (other than here, which gives you again the same 3 fields).

3. Tried to find if there are other fields that I missed that could be used somewhere else. I don't even know if resourceName or etag are reliable and unique for querying.

4. Tried to add more fields to the query, despite the docs talking about just 3 fields. Failed, of course...

5. There is a function called copyOtherContactToMyContactsGroup (here) which seems that it will copy contacts to the main group of contacts. I guess that if I use this and then query the contacts themselves (not just "other contacts"), I could get the needed information. But this is a waste of time and can pollute the user's address book, even temporarily. I would have to make sure I delete the contacts from there right after I add them...

EDIT: tried this too, and while it seems to work, I don't want to use it as it pollutes the address book with contacts that the users hasn't added. Plus I got sometimes an image which is simply the letter of the person with a background. This is the code of it:

result.firstOrNull { !it.names.isNullOrEmpty()&&!it.emailAddresses.isNullOrEmpty() }?.let { person ->
    val request =
        CopyOtherContactToMyContactsGroupRequest().setCopyMask(
            "emailAddresses,names,phoneNumbers")
            .setReadMask(
                "addresses,ageRanges,birthdays,coverPhotos,emailAddresses,genders,metadata,names,nicknames,occupations,organizations,phoneNumbers,photos,urls")
    val copyResult: Person? =
        services!!.otherContacts.copyOtherContactToMyContactsGroup(
            person.resourceName, request).execute()
    Log.d("AppLog", "success $copyResult")
}

Also, this seems to be extremely slow compared to simple queries, and there is no batch operation for it either. In addition, testing it out, I think it can cause various server issues related to quota being reached (about 180 per minute or so).

I think that as the website shows the photos and can show you per-contact information, we should have this API too, no?

6. I thought that maybe I could create a new group (label) , copy the "other contacts" to there, and then fetch the information from there (as it allows to get more fields), but the docs (here) say that it was possible before, and not anymore:

The only system contact groups that can have members added are contactGroups/myContacts and contactGroups/starred. Other system contact groups are deprecated and can only have contacts removed.

This is a bit better solution (if it worked) as I can remove groups safely without affecting actual contacts.

The question

What's the best way that I should use in order to get all kinds of information (like normal contacts) about each item in the "other contacts" list? Is it possible without copying to the contacts list and without getting "fake" photos (of the contact initial letter) ?

from How to get full information about "other contacts" using People API?