Hi,
I don’t tend to need to calibrate.
You could try xDrip. Similar features to Diabox.
But I use “GlucoDataHandler” to hijack from Librelink to send to xDrip.
There is also Juggluco. Bit more of a faff when starting a new sensor in the sense you need to scan again in the app after Librelink..
All apps mentioned can also send to a smartwatch with the complimentary wear app installed?
The Juggluco wear app for watch will also take a feed directly from the Libre should you wish to ditch the phone & monitor on an appropriate watch for swimming…
Cross that bridge with a watch should you decide to take the plunge?