I mean the core of populism isn't about being deceitful for your ideology or slimy. Populism is largely about framing yourself and your policies as for the ordinary person, other with a rejection of elites often fit into it but not required. For example of just the names people have used, Trump is a rightwing populist and Sanders is a leftwing populist. Populism is a vehicle for how you get your ideas out rather than being indicative of much more in practice. Where Edelgard's whole thing is about leveling the playing field against the nobles and crested, which fundamentally is a populist framing of her ideas and goals.
Wrt being a strongman it could be argued more in my eyes but the main reason I say that is she still is heavily authoritarian with elements of meritocracy in her approach. So regardless of her potential intent, there is such a clear overlap in terms of strongman tendencies that I think its fairly accurate.