I don't know if this game will work for you, but it's very different from Fire Emblem: Three Houses.
It's a very plot-heavy game in that a lot of things happen, but it's relatively economical in its presentation compared to many games like it. Each adventure game segment is a 10-20 minute chunk that conveys something meaningful, and it doesn't waste much time on needless repetition, trusting the player to use the Analysis features if they're confused or want to learn more. The customization around the strategy segments is relatively straightforward, primarily focused around upgrading a set of weapons for each character. Unlike a lot of visual novels that have lost me, 13 Sentinels presents its plot hooks quickly and maintains forward momentum throughout.
Where it bears similarities to Fire Emblem is that the characters don't go too far beyond the stock anime archetypes they're built from. They each have their own arc of character development, and there are many different kinds of satisfying interactions among the cast, but they aren't individually all that textured.
Thanks. Maybe I check it out, because I like the art and the premise.