GPS Selection

So, according to youtuber Painless360, the GPS that comes with the dolphin pro is not great (source).

It's the Beitian BE-220, which uses the u-blox M8N chip which has the following shortcomings:

• Slow satellite acquisition: Some have said that it takes long times (5-10 minutes) to get a reliable 3D fix even under clear skies. (source)

• Pre-arm instability: When using EKF2/3 (Copter) or EKF3 (Plane), the module may delay or fail pre‑arm checks due to unstable velocity or position locks. (source)

• Inconsistent satellite fix in iNav: Mulitple pilots note the BE-220 often fails to get any satellite lock in iNav, despite correct wiring and settings. (source)

Painless360 recommended a HGLRC M100-5883. This comes with an integrated compass and a u-blox M10 chip, which is signfiicantly better than the M8N chip. It's also not that expensive, however, it seems like I have to get it from Aliexprss so it might take a while to come.