There appears to be some missing options in the config pages for FRR/OSPF for setting the ospf area type.
Maybe I'm just not seeing it but for our case we need to be able to set 'area x.x.x.x stub no-summary' in frr.conf.
In pfsense there's an "Areas" tab to FRR/OSPF that allows you to define areas as normal/stub/stub no-summary/nssa/nssa no-summary. If this exists in opnsense I'm unable to find it.
I found this issue on github for this feature:
https://github.com/opnsense/plugins/issues/1971 (https://github.com/opnsense/plugins/issues/1971)
If a dev sees this and can reopen that issue that'd be wonderful.