Mega 360 Compatibility I found.

360 Mega compatibility and FAQs from Humminbird:
MEGA 360 Compatibility:
Direct Connect MEGA 360 Sonar Transducer:
SOLIX 15 CHIRP MEGA SI+ G2
SOLIX 15 CHIRP MEGA DI+ G2 CHO
SOLIX 12 CHIRP MEGA SI+ G2
SOLIX 12 CHIRP MEGA DI+ G2 CHO
SOLIX 10 CHIRP MEGA SI+ G2
SOLIX 10 CHIRP MEGA DI+ G2 CHO
HELIX 12 CHIRP MEGA SI+ GPS G3N
HELIX 12 CHIRP MEGA DI+ GPS G3N
HELIX 10 CHIRP MEGA SI+ GPS G3N
HELIX 10 CHIRP MEGA DI+ GPS G3N
HELIX 9 CHIRP MEGA SI+ GPS G3N
HELIX 9 CHIRP MEGA DI+ GPS G3N
HELIX 8 CHIRP MEGA SI+ GPS G3N
HELIX 8 CHIRP MEGA DI+ GPS G3N
(Note that due to a hardware limitation in the SOLIX “G1” and HELIX G2N, MEGA 360 cannot directly connect and be controlled by these models)
Indirectly via an Ethernet subscription to a SOLIX G2 or HELIX G3N model:
All SOLIX G2
All SOLIX “G1”
All HELIX G3N
All HELIX G2N
FAQ:
How does the MEGA 360 connect?
The new MEGA 360 connects the same way that a conventional 2D, DI, or SI transducer connects.
The MEGA 360 can be connected directly alongside a second transducer with a transducer splitter cable. For HELIX units use: 9 M360 2DDI Y (720107-1). For SOLIX units use: 14 M360 2DDI Y (720108-1).
If the MEGA 360 is connected in addition to another transducer, sonar options will be 2D, DI, 360, and SI from the MEGA 360. Stand-alone SI will not be an option while the MEGA 360 is connected
Can I connect other transducers at the same time as the MEGA 360?
Yes
HW, HW/MEGA DI+, HW/MEGA DI+/MEGA SI+ imaging transducers can be connected in conjunction with the MEGA 360. Built-In MEGA DI+ from a Minn Kota trolling motor can also be connected at the same time as a MEGA 360.
A transducer splitter cable is needed to do this. Use a 9 M360 2DDI Y (HELIX) (720107-1) or a 14 M360 2DDI Y (SOLIX) (720108-1) accessory cable.
If an MEGA SI+ transducer is connected with one of these y-cables, the Humminbird will not be able to get SI data from the MEGA SI+ transducer – only HW and MEGA DI+ will be available. However, the user can get MEGA SI data from the MEGA 360.
US2 Minn Kota transducers and Humminbird transducers that are 83/200 or 50/200 cannot be connected at the same time via Y cable with a MEGA 360.
Airmar High-Wide transducers can be connected at the same time as a MEGA 360, but Low, Medium, High, and 50/200 kHz Airmar transducers cannot be connected at the same time.
What is the MEGA 360 wet switch used for?
The MEGA 360 wet switch automatically stops MEGA 360 pinging/rotation while the transducer is out of the water, in order to prevent wear and tear.
The MEGA 360 and Humminbird unit remember if the user had pinging turned on or off, and when the MEGA 360 is put back into the water, it will resume the users selected previous operation mode.
What other frequencies does the MEGA 360 support besides MEGA?
The MEGA 360 can ping at MEGA and 455 kHz frequencies.
How can I use the MEGA 360 to mark waypoints and spot-lock points?
The MEGA 360 can be used to create waypoints and spot-locks.
In order to do this a Humminbird AS GPS HS (408400-1) or Minn Kota i-Pilot Link BT Heading Sensor must be on the network.
In order to use Minn Kota i-Pilot Link BT Heading Sensor data:
SOLIX must be running software version 3.400 or later
HELIX must be running software version 1.940 or later
i-Pilot Link must be running software version 1.270 or later | i-Pilot Link remote version 2.010 or later
How is the MEGA 360 powered?
The MEGA 360 is powered by a separate power cable that connects to a 12 volt power source.
Is the MEGA 360 easy to install and remove?
The MEGA 360 has connectors and a mounting bracket that are designed to be installed or removed in 1-2 minutes.
What trolling motors is the MEGA 360 compatible with?
The MEGA 360 is compatible with 45” and 54” shaft-length Minn Kota Ultrex, Fortrex, and Maxxum trolling motors.
Is there a transom mount version of the MEGA 360?
No
Can the MEGA 360 be shared between the HELIX and SOLIX over Ethernet?
No.
If the MEGA 360 is connected to a SOLIX – it can only be shared over Ethernet to other SOLIX units.
If the MEGA 360 is connected to a HELIX – it can only be shared over Ethernet to other HELIX units.

1 additional note not specifically listed:

AS GPS HS antenna is not included with MEGA 360 like it was with 360 G1 ...

Rickie