This is a user to user forums. Mojang (likely) doesn't check here (often) and anything they did read was most likely just be read rather than responded to. They won't give direct e-mail responses and I'd suggest removing your e-mail for spam purposes.
A more direct way to reach Mojang would be here, although it's still largely user to user and they just watch it (but they at least do that part).
I'll still give my own feedback on your suggestions.
Shulker box inception is just infinite storage. That's not only broken, but just adds more to inventory management time.
Let's look at a scenario where you can only nest them one layer deep.
Counting only the space ender chests offer (27 spaces), that turns 729 storage spaces into 18,954 storage spaces (I subtracted the original 729 spaces as these would now be holding shulkers which are holding items).
Depending on how "light" you are with your inventory, you can more than double that since you can hold 25% (and then some due to offhand) more inventory space than ender chests can hold.
What do you need the ability to have possibly well over 40,000 "inventory" spaces for? I say inventory because a portable ender chest with shulkers effective adds to your inventory space. It's already able to be well over a thousand. And then most items stack to some degree, so this becomes a silly high number things to have immediate "inventory" access to.
Likewise, the enderchest has limited storage space to balance it. Originally, it only offered 27 spaces because shulker boxes didn't even exist. Now that they do, the ender chest is severely useful as it is.
I think bundles were iceboxed for now because Mojang didn't feel like they addressed the inventory issues well?
The big issue with the inventory, especially in modern versions due to there being many more items, is it's easy to clutter your inventory with a lot of things that are only few in count, so bundles were sort of supposed to alleviate that. I can't recall how they were going to work but to me, it sounds like an unecessary thing that doesn't serve much differently from a shulker box (I'm fairly sure they were intended to be like limited shulker boxes that you could access early game though). In my opinion, just allowing more inventory space (like another row, or if they go with columns for more hotbar space then a couple/few more of those) to make up for all the added items in the game is the way to go. It gives more inventory space early but doesn't add another thing that's just a clone of another thing.
The last two you would have to elaborate on. What are "upgrade enchantments"? They already come in different level tiers which sort of are the upgrades, and they're already borderline broken, so making them stronger means we need to make mobs stronger, which just makes you super fragile without armor or enchantments (and this is already close to this case as I'm finding out in a recent world I'm playing where I can't enchant stuff). Same for more redstone stuff, you need to give specifics to what functionality/items you're suggestion. Broad suggestions aren't much to work with.