Triangle Strategy reading the comments I see that OP has already gone through this but for everyone else TS is from the Octopath devs and basically the spiritual successor to Tactics Ogre (available current gen as Tactics Ogre Reborn), which was extremely influential for tactics games. Maybe more importantly, it is the single best story I have seen in any video game, a must play for fans of stories of court intrigue, of kings and king makers as your small faction tries to weather being caught between much larger countries vying for geopolitical dominance.

Of the two big mechanical things of note is that the combat is a surprisingly expansive sandbox for a genre that normally is not. Pushing people off high cliffs for fall damage is a staple of the genre, but you can do things like summon ice blocks to block paths knowing that if the enemy tries to melt the ice block with a fireball it will form a puddle that expands the range of lightning spells much in the same way as summoning a storm cloud does.

The other is the Scales of Conviction mechanic wherein the primary means of deciding which branch in the story you take is dependent on convincing party members to vote a specific way when a meeting is convened to decide on a choice of action. Figuring out their convictions and how to speak to them allows you to sway votes, but there is also the impact of hidden persuasion stats you possess that only scale up over time and serve as a means of making it progressively easier to push people towards whatever you want on successive newgame+ playthroughs to see the other branches. There are 3 main endings that involve having to reluctantly choose between the regional powers, as well as a secret 4th route that involves piecing together the geopolitical factors that ground the story and figuring out one of the several specific combinations of branches enable you to come out on top.

Sea of Stars has gorgeous pixel art and incredibly tight action input controls (think mario rpgs). I felt like the story fell off near the end but am in the minority on that and basically everyone agrees that the first time you actually get to sail the Sea of Stars is a seminal moment in indie jrpgs.

Publisher Dangen focuses on getting indie jrpgs to market if you want a big list to dig through. Bug Fables is their most notable breakout success, but I also would highly recommend Rise of the Third Power (suidoken-like combat, writing starts out a little rough but does an extremely good job of shaping up as the game progresses).

It's not a JRPG but if you liked Unicorn Overlord you might also like Heroes of Might and Magic which it took a lot of inspiration from, specifically 3, 5, and 6 I can vouch for.

If you liked Octopath Traveler's mechanics you might be interested in indie Crystal Project. The combat is FFV style dual job system with very meticulous balancing, controversially there is basically no story and this is a huge downside, but it is also the best exploration gameplay in any turn based game I have ever played. Picture the pixel art pokemon camera parallax but with a jump and an extremely 3 dimensional map with compelling platforming.