Turn Order prototype

It's definitely an interesting idea, though it could definitely be expanded on for a more unique system, like you said.

Anyone who's ever picked up an RPG can definitely see the appeal in having the tank or the sweeper go first with party damage reduction, single target/aoe physical/magical burst, taunt/aggro moves or enemy debuff skills while the healer goes last. 

Knowing when the foe will attack is nice but doesn't mean much at the moment for a prototype where you don't really have to worry about taking big burst damage in the current system.

Of course, with the system you're proposing, being able to visualize when the enemy will act is crucial, such as having a turn order sequence that also shows who the foe plans to act and what skill they plan on using (the latter can be deemed optional, but the strategy aspect depends on knowing/predicting what enemy skill you need to have the party react to in advance, such an area of effect firestorm or a high damage single target physical move with low accuracy that can be countered by an evasion buff, etc.)

But more importantly, a system that lets you decide turn order is going to inherently draw a lot of value from what skills each party member has and how fun it is to chain skills together during combat flow.

For example, Sawyer Friend's recent game jam entry, Meeting of the Selves, has a fairly robust puzzle/jrpg system with turn order where you can focus on offense by weakening the foe with a resistance lowering debuff and then chain the mage's magic damage skill together for great value, a situation where turn order is crucial because the debuff only lasts one turn.

In comparison, this prototype demonstrates the basic idea but the available skills leave a lot to be desired for the moment. Harold has his usual Heal and Spark, Therese has no skills, Marsha has Fire and Lucius has Heal. All useful skills but they don't flow or chain together well in regard to having the usual jrpg strategies like aggro/taunt, buffs/debuffs and exploiting enemy elemental weaknesses. Plus, game balance can become tricky in a hurry when you want to decide on how tough/powerful/dangerous the foes are and how much pressure you want to put on the player to plan ahead and use defensive skills to mitigate incoming burst single or multi target damage or seriously crippling debuffs that require skills or items to cure, something that is standard in many RPG system.

The OTB Octopath Traveller system sounds like it has merit, but I'm not sure if the dynamic nature would do much to improve the strategy aspect. Octopath Traveller and similar titles like Crystal Project plus Time Break Chronicles are fun and easy to pick up and play because it's not difficult to react and recover to burst damage if you remember to hold MP and healing items in reserve during a pinch, which most players lean into by default becuase of all the RPGs they've/we've played over the years.

The current 'choose turn order and skills at the beginning of each round' seems like it has more value to be extrapolated upon for the strategy aspect. I know that most JRPGs have a set turn order system so the player can focus on choosing party skills and reacting to enemy skills, while turn order is something that can be altered and shifted with certain skills in certain RPG systems (Time Break Chronicles has personalized skills that let a character use their turn to give an extra turn to a different character) but not something you normally pick at the start of every round. Done well, and the player will have a lot of fun with deciding turn order as well as party skills. Otherwise, the player will just go with Character 1-2-3-4 / H-T-M-L and spam attack and damage skills.