[eld]

On version 8.30 (of Mar 10, 2023), I discover a new menu in settings:
Radar Altimeter, with parameters :
enabled/disabled
Antenna Height
Maximun display altitude

it's to support GHA 15 or other device ?

When enabled, field display on G5 HSI

 

[Avanza]

It supports the certified GRA 55 radar altimeter.
From ARINC 429 to GAD 29 to CAN-bus to G5.
from software 9.31 as of August 31/ 23 the GHA 15 is a new option.

Good luck