Thank you for taking the time to reply.
I'll keep an eye on your work. I've got a couple assets in the last couple days but I can definitely see myself getting your stuff in the near future. The guns themselves look good already but I think the characters really stand out as stylized with the PSX look but with a touch of modern polish if that makes sense which makes them look quite good.
Regarding how the bundles work I'm quite new to platform as well and I'm only on customer side for the time being. Maybe ask itch.io for more info or other creators if you have any contacts. I do know that a trick that might work is creating a separate "mega-asset" that can't be bought but is also included in the bundles you have now like you include any other asset and then whenever you release a new asset you make an update to that mega-asset with the new files. Since it is in the bundle buyer's inventory they can just go the mega-asset page and download the new content added.
I bought stuff from ELV Games recently and I think they use a strategy like this. Keep in the mind, this might not be the best way to do it but it's just something I've seen that could work if you decide to go that route. I'd still advise checking with itch.io on the best way to do it.
If you do decide to make the bundles include future updates I'll grab'em for sure :)
Keep up the good work. With this level of quality I'm sure you'll get recognition bit by bit.
EDIT: Added paragraphs for better readability