If you have the same goggles as I do they come with a 48 channel 5.8ghz Dual Diversity receiver built into the screen so all you need is a matching Txr and antennae.
I usually use the TS832 Video transmitter, they are around $35.00 from AliExpress.
Technically you shouldn’t go past 25mw without an amateur or specific licence but no, 600mw will give you good range, I also have a 400mw version that runs a lot cooler and gives just as good a range. Just make sure you match the Tx & Rx antennae, if you circular polarised then they both need to be either left or right polarised.
I reckon the antennas I have (some of which Ron made) are all good to go… I’ll muddle through them all, and see if I can get it all going with the Matek FC.