iraqi_sunburn If you just want swipe typing, you don't need Gboard. Heliboard supports that if you install its version that supports user libraries. On the releases page, you want the HeliBoard_1.3-release.apk version. Go through the settings both to enable it and to customize it to your liking. If you want a voice to text service, FUTO Voice is very good and integrates well with Heliboard.
You can manage and update apps using Obtainium.
SMS Backup & Restore for backing up, restoring, and transferring SMS, MMS, and RCS messages. It does a better job than Google's backup feature.
For contacts, either host your own using nextcloud kr use a privacy respecting service like proton or tutanota. To actually sync it, if your service doesn't provide it, some choose to use EteSync or Davx5, though this could be security issue. It might be simpler to just export/import your contacts to your phone and keep the master copy stored on the service's servers.
For google voice, it works very well using a progressive web app (I.e. click install from a web browser). You won't get notifications since PWAs don't usually support it, however, google voice allows you to forward voicemails and SMS to Gmail. If you setup an IMAP client like K-9 Mail, you can have it fetch new emails every minute or so. Not as good as real time, but good enough if you're comfortable calling people back. The PWA will also allow you to make calls directly from the browser by first calling your linked number and then calling the dialed number (using the google voice caller ID).
I'd personally just use a normal browser to create a Google Maps PWA than use a probably inferior webview app. You may want to enlist the help of additional browsers to segment activity further if staying within one profile. Brave is often recommended.
For AI chatbots, I can't help you with open source models, but I just use third-party websites that give free access to chatgpt API. There are a bunch. I access it through my web browser. You can bookmark the pages or add to home screen. I access them with a VPN in a browser that doesn't contain personal info.