Octopath Traveler is basically 2D. It doesn't get much lower budget than that.
I'm not proud of this, but I do play some Compile Heart games. That's about as low-budget as I'm willing to go. If a game in 2018 can't even bother to get into the 3rd dimension, I'm out.
First of all is Octopath not 2D. This are 3D-models with pixel-art textures. From a development standpoint it is more effort than cheap 3D-models and textures. As I didn't know Trails of Cold Steel I watched a video - yes that, cheap textures and models, fast and easy to produce. Often standardized assets. Pixel-art is often more work, but moreover Octopath traveler has changing styles depending on the region. I'm pretty sure Octopath budget turns out to be higher than Trails of Cold Steel. Or compare with Persona with indicidual style and assets, much more work. And content size obviously influences budget as well. And don't get me wrong, I don't want to say Trails is bad, turn-based RPG is so niche it has low sales, you have to optimize costs to make the project profitable. That's clearly understandable.
So your choice is basically 3D instead of 2D. You don't talk about budget, you talk about 3D-graphic. That's fine, but wasn't clear before. Of your examples Valkyria Chronicles 4 is on Switch too, DQ 11 will come later. But yes, with this specific set of restrictions, the game set gets smaller. Disgaea what I named before is also 3D, but an old port. Later this year comes Pokemon Let's Go, which is a classic turn-based RPG, but not everyone is into Pokemon and Let's Go actually reduced the number of fights.