I don't play "other indie roguelikes" so I don't know what they look like and don't think it's relevant. Your task is to make the best possible game by your definition, not to compare to what all the other people are doing. Doesn't matter what their UI looks like.
And in general "missing too many UI elements" is the wrong question. The fewer "UI elements" a product needs to communicate its core message, the better. (In this case, what's better: A game with very detailed, thorough tooltips explaining how each mechanic works, or a game with no tooltips & no explanations but mechanics that you can understand simply by playing the game?)
"Ugly" UI is in the eye of the beholder - minimalism and rough edges on a project like this give it charm. But regardless you should trust your instincts and not what someone on the internet says because it's your thing not mine
I think You Do 1, use right side for output, left side split up your gems and inventory. You don't need any additional popup UI besides settings. Just on hover for gems/inventory
Been a min since I played the demo/v0.1 but was there like viewable stats? You are now +2/+1, etc.
You can add flavor to the game by having the enemies /boss say stuff to your output. If the output of a round isn't enough to fill it up you can have it persist and add a divider for each new fight so a user can look at the past logs on scroll.
Other nice to haves for your UI (and again disclaimer I haven't played din a minute)
add a light grid for the bejewl
randomly label dungeon squares as a certain terrain and modify the fight field terrain to match your cell
integrate the battle UI pieces into one cohesive piece vs separated heavily as they are now. Kinda like a rectangle box with a square box in the center of it, different bg for board vs new background
on being hit the fighter moves back for a second, on swing the fighter moves forward. You don't resolve both sides simultaneously this way but i think it looks a lot more fluid and shouldn't add much time to resolving a move. Also helps with making your output log make chronolog sense to users
It was very clearly not a math question and you don't need to be act like a wiseguy.
The question is whether it's interested to play a game where your "decisions" (think hearthstone cards) are just duplicates (you whole deck is just different reskinned 2/3 minions).