Hi! I have some questions and the topic's title is pretty clear :D I hope I didn't miss an already existing topic! In that case I'm so sorry! Feel free to link it and I will read all the stuff :) So, as I was saying: How does the BHH work? Is there a ping group (fingers crossed)? How does humming power Crystal works?
Thank u in advance!

BHH restocks one item at a time randomly throughout the day. There's no ping group because there's only the one item - people who get lucky enough to see something will generally just click Buy as fast as possible. There's an additional guide here: Quick Guide to BHH

The fragmentizer will turn items of most rarities (specific list copied below from the fragmentizer page) into 1-2 (I think?) humming power crystals each which are the currency used in the Crystal Shop. I don't know if there's a specific breakdown out there for which rarities give how many crystals, but IME it doesn't really pay to hunt specific rarities of items to frag. I usually just look for all fraggable items under a certain price and it averages out to about 1.5 crystals per item. Fragging recently because of Keelhauliday has given me a slightly better rate than that but I don't know if that's a coincidence. I haven't paid super close attention

Fraggable rarities: R1-99 (restocking items), 101 (retired items), 115 (melody items), 150 (special items), 160 (game prize items), and 175 (holiday items)!

All rarities average out to ~1.5 crystals. With two exceptions: Rare 66-85: ~2.5 crystals Super rare 86-99: ~3 crystals

However, is correct. Its not worth it to look for the higher rarity items because they usually sell for far more than the value of the crystals you get in return.

If has been vending from oceans depths and is fragging directly from there, then its not coincidence that they're getting slightly better results than usual because OD gives out items up to R80, so there are going to be a few more Rares than usual. The other vending machines give out a max of R60.

Thank you both, so much! And the only use of them is to convert them in order to buy from the shop, right?

buy from the shop, or sell to other people. you can't un-convert them once turning them in.

Perfect thank you! It's all clear now :) Subeta has so many features... it will take a while to manage them all!