INAV Ground Station Usage with DJI Compatible OSD

DJI Compatible MSP DisplayPort OSD
INAV 6.0 began supporting a special MSP DisplayPort mode compatible with DJI's incomplete MSP DisplayPort implementation (such as the DJI O3 Air Unit). INAV 6.1 further extended support for BetaFlight 4.4 HD canvas dimensions.
Different flight controller firmware uses different OSD characters and elements, requiring different fonts. BetaFlight uses a single-page font supporting up to 256 characters (glyphs), while INAV uses a dual-page font supporting up to 512 characters. DJI's font is based on BetaFlight's single-page font but is not identical.
Although DJI and INAV fonts have partial overlap, a one-to-one mapping cannot be achieved. Unmatched characters will display as ? on the OSD.
How to Enable
You can select the DJI43COMPAT or DJIHDCOMPAT video format in the OSD tab of the Configurator, or set it via CLI command:

set osd_video_system = DJI43COMPAT 或 set osd_video_system = DJIHDCOMPAT

Limitations

• You must manually set the canvas size to HD in the DJI goggles' Display menu and set it to DJIHDCOMPAT in the Configurator.
• Unsupported characters will display as ?.
  Frequently Asked Questions (FAQ)
  Q1: I see many question marks on my OSD?
  A1: This is normal and indicates that characters not present in the DJI font are being used.
  Q2: Is it compatible with G2 and original Air Unit/Vista?
  A2: Yes, it is compatible.
  Q3: Is this a replacement for WTFOS?
  A3: No. WTFOS is a complete MSP DisplayPort implementation for jailbroken Air Unit/Vista/Googles V2 that fully supports all INAV OSD elements. If you can use WTFOS, it is recommended to use it instead.
  Q4: Can INAV fix DJI's issues?
  A4: No. OSD rendering is performed on the goggles or Air Unit side, which INAV cannot control. It is recommended to provide feedback and request improvements on the official DJI forum.
  Q5: If DJI adds new symbols to their font, will INAV update to support them?
  A5: Possibly. If the new font has more mappable characters, INAV can adapt. However, the best solution remains DJI's full support for MSP DisplayPort.
  Q6: Can text be used as a substitute for missing characters?
  A6: Technically possible, but this would complicate OSD rendering and configuration, so this method is not currently recommended.
  Q7: Does DJI support true Canvas Mode?
  A7: Actually, no. What DJI calls Canvas Mode is actually character-based OSD (i.e., MSP DisplayPort). True Canvas Mode is supported by FrSky's PixelOSD, such as on certain Matek F722 flight controller boards.
  ————This article is referenced from the INAV official website: https://github.com/iNavFlight/inav/blob/master/docs/DJI%20compatible%20OSD.md