Betta Fish: Introducing my fish, my setup and myself

Hello everyone! I am a returning hobbyist who has had some Bettas in the past but took a hiatus from the hobby for a while. I have a 90 gallon fancy goldfish tank but was kicking around the idea of a planted Betta tank for some time when…well. I was at the pet store ACTUALLY just looking for plants, not expecting at all to find my literal dream fish right there. I have always wanted (and never kept) a blue butterfly half-moon, and guess what I saw sitting in one of the small display tanks? Exactly. The tank was pretty bare, the filter was strong and the poor fella rested kinda stuck against the overflow filter intake of said show tank. Besides that his fins weren't torn or damaged, his skin looked fine and all, but I knew the stress would get to him sooner or later, so I felt compelled to act quick…I basically set up the tank on a whim last night and immediately got him in there. Now I was lucky because I was able to use fully cycled sponge from my 90 gallon goldfish tank to basically provide a fully cycled filter from the get go, but I also added some starter bacteria to additionally jump start the cycle.

So this is my new boy's setup! I know cube type tanks are not suuuper ideal dimension-wise, but it's what I had to work with. It's a five gallon tank, with Egeria Densa, Vallisneria spiralis and I forget the name of the bigger leaved plant in the front…oops (some photos clippings at the top). I also wanna get some type of floating plant in the future to create more shade in the tank. There is also a photo of the lid of the tank attached. The filter is a small air pump driven sponge filter. Eheim heater is set to 26 °C. Little SpongeBob hideout is kinda corny but I got it as a well meaning Christmas present for my goldfish (!! can you imagine lol), sI realised it was the perfect size for a betta, I sanded down any rougher edges and made sure the windows are big enough for him to easily swim through.

For food I got the pellets which you can see on the last photo as I have read this food is high quality and has 56% crude protein, however I also bought an assortment of frozen food to supplement.

Am I doing okay? Anything else I should consider or add? I was thinking about tannins via dried leaves, however I am still confused about possible pH fluctuations this could cause…any input appreciated! ❤️🌱