[Quoth]

/me gets out spade and keeps digging.

I think the My Lists/Wish lists feature via browser on the Amazon website is a solution and more flexible (multiple lists and not just Kindles). Does that work on the Kindle Browser?
Allegedly you can even add non-Amazon items, but I've never tried it. Though my same login & pass works on USA, UK and German Marketplaces those have separate lists. Possibly only Japan needs a separately created account.

Irish Kindle owners can swap their Kindle Account (all the kindles on the Account) to be USA or UK, which affects prices, but the geo-limited sales are the UK list. I've no idea what happens to the "on device" Kindle Wish List, as I never knew it existed.
I see the recently updated PW3 (5.16.2.1.1, it was on 5.13.x and I wish I hadn't updated!) has a Reading List via Home (which seems mostly Adverts). It is some sort of list of books I already have and have read, not a Wish List of books to get.
No idea how that was populated. It's generally a ghastly GUI vs older.

The older FW on another PW3 is 5.12.4 and seems far better to browse the on device library. Its "Home" is a Library view like My Books on Kobo and better than the library view on 5.16.x but not same sorts and filters.

It also has "Your Reading Lists" on the menu, but also it's books I already have and have read, not a "Wish List".

I can't see a "Wish" type list on any Kindle I have, only on my Accounts on Amazon Marketplaces via web. To me a "Wish List" isn't a TBR pile, but a list of books (or anything) I might get. My UK Marketplace has Kindle, paper, video and other stuff lists. The DE and USA just have one list each.

The 5.12.x in Advanced Options > Home & Library lets you block marketing and have only a Library view.
The 5.16.x doesn't let you turn off Marketing on Home & Library. Instead there is are three options as to how Collections are listed. One option ONLY shows them under Collections, another is Favourite Collections always and third is traditional option of also listing Collections.