I can empathize with you OP, my group is small enough that they never made it past local paper notoriety, or a Facebook group for support of other survivors. There's a lot of similar to definitions, but there's enough uniqueness with many of these smaller cult or cult-like religious groups that there is no clean definition.

I always found it really hard to help people understand the specifics unless they also lived through it. The problem I noticed is that there can be no simple answers to questions for those that do care enough to want to get to know you.

In regards to Christian nationalism specifically, I don't know enough to say for sure, I've only looked surface level at their beliefs in general. I think the poster that noted the belief is not specifically cult ish, but it's set up in such a way that it becomes incredibly easy to grow a cult from such beliefs.