Query public group channels by non-members

I would like to support 1:1 messaging between 2 member users with all the features that Public Group channels have. Push Notifications of all sent messages is desired in particular. I would also like to support non-members to be able to query and see these same channels (for read-only view access).

It seems that Open Channels works for what I need except w.r.t. push notifications. Public Groups do not return results when the query is executed by non-members. This is what I have so far on the query side. Works for members but not for non-members.

Does anyone know of a solution?

// Find a channel associated with...
var urlFilter: String = // my ID string

let listQuery = SBDGroupChannel.createPublicGroupChannelListQuery()!
//listQuery.limit = 1
listQuery.includeEmptyChannel = true
listQuery.channelUrlsFilter = [urlFilter]

listQuery.loadNextPage(completionHandler: { (groupChannels, error) in
    guard error == nil else {
        // Display, log, handle error

    if let channel = groupChannels?.first {
        let channelVC = SBDChannelViewController(channel: channel)
        let naviVC = UINavigationController(rootViewController: channelVC)
        capturedSelf.present(naviVC, animated: true)

Update: Added the follow param to the query. Results in the channel being fetched! Unfortunately the display of the SBDChannelViewController happens only momentarily and then is auto dismissed. And, now to this next nut to crack.

listQuery.publicMembershipFilter = .all