Looking on the C9300X-M datasheet site on the Meraki website, it lists the optional accessories at the bottom of the page. The Cisco page lists more items, in particular the C9300X-NM-8M, which isn't listed on the Meraki page, is every module on the Cisco page also compatible with the Meraki firmware?
Catalyst 9300X-M Datasheet - Cisco Meraki Documentation
Cisco Catalyst 9300 Series Switches Data Sheet - Cisco
I'm asking as it'll be plugging into an MX85 and ideally wanted to stick with 10GbE rather than SFP+ or SFP28 and optical cabling.
If not, i'll ask the Meraki support to clarify.