Murcielago
Addendum: I had just looked for this thread and couldn't find it - here it is:
Not having a SIM or disabling all the SIMs disables authenticating with or using specific carriers whether it's through cellular or Wi-Fi. Wi-Fi calling and texting do exist. These are different things. Cellular can be used for emergency calls and emergency alerts without a subscription. Carrier subscriptions can be used for Wi-Fi calling and texting without cellular including with airplane mode enabled if you enable Wi-Fi, which is permitted. LTE-only mode is not really relevant to this. Airplane mode is the way to disable cellular. It makes sense to both disable cellular via airplane mode and disable SIMs at the same time if you want cellular disabled and also want Wi-Fi calling/texting support disabled too.
source: https://discuss.grapheneos.org/d/19535-does-imei-get-sent-to-towers-on-gos-without-a-sim/3