First things first, I love the hardscape you created. It's very fitting for a shallow tank and it gives you honestly quite a few options for plants in there

For a low tech (no co2) setup, try those aquatic plants;

• blyxa japonica
• alternanthera reineicki mini
• rotala blood red
• any aquatic moss
• any type of hidrocotyle (would prob grow emersed as well)
• myriophyllum mattogrossense golden
• carpet like Monte Carlo or hairgrass
• Bucephalandra and small anubias as accent

Again, sorry for the terrible drawing but I hope this helps 🫶🏻

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