Yes, like fighter radars. The US, for example has a TPS-77 radar with GaN since 2018 or so, israeli ELTA has some similar GaN radar. Those are both mobile tactical air surveillance radars for the air defense network. Yet, in these years since then, no one came out with even mentioning that they're working on a GaN based fighter radar. Could it be it still requires a lot of additonal effort, on top of getting GaN to work on larger arrays? Maybe the cooling requirements are still not solved for the crowded space in fighter noses?
AN/APG-79V4 is a GaN AESA which is a radar upgrade for *legacy* F-18 hornets, that the USMC have already ordered.
Saab also offers a GaN AESA for Gripen that they're well underway in development for.
I think the only reason why it "seems" like there aren't many recent GaN fighter radars is probably because many fighters are already in production or in advanced stages of development with GaA, and going with GaN means its own developmental path needing time and money and setting timelines back further -- I suspect many customers just want an AESA equipped fighter fast
But as we can see, some GaN fighter AESAs already exist in the west, and I wouldn't be surprised for more to emerge in the next few years as developmental cycles for projects begun in the recent past yield more radars.
I also wouldn't be surprised if the new AN/APG-85 for F-35 Block 4 is GaN.
And similarly for the PLA, I would expect radars that started development in the last 2-3 years to be GaN, including for fighters such as J-35/XY, J-20B/J-20S etc. But obviously for the PLA they're probably not going to tell us if they're GaN or not.