I saw this recommended elsewhere on Lemmyna few days ago and have given it a shot after a month or two trying AnySoftKeyboard - its great.
It may not be as obviously feature laden with additional keyboards etc as ASK but it has much better defaults - all of the extra punctuation is where my fingers just expect it to be after a long time on SwiftKey.
I’ve just spent the last week with Gadgetbridge for my Forerunner 265.
Previously I had Garmin Connect installed on a separate Android user profile with Google Play Services enabled (GrapheneOS). I would only go in there once a week or so and look at the Garmin info as it synced over.
Gadgetbridge is working pretty well - the great majority of everything I actually cared about viewing is accessible. I also have an always on BT connection for notifications and music controls which I was missing out on before.
That said, there are a few drawbacks
Gadgetbridge often uses bar charts for time-series data where Garmin uses a line chart. e.g. Stress is a series of 1px thin vertical lines with colour to indicate bands. Garmin’s single line which swaps colour is far clearer.
Its easy enough to open the GPX file in an external map viewer, but you can’t see its alongside heart rate etc and the track won’t be heatmapped for speed as in Garmin.
Personally, I’m willing to live with these compromises for the privacy, certainly for another few months trial.
As it seems easy to setup a regular export of Gadgetbridge data, I might make it a coding project to implement better visualisations in Python.