And... it's gone (D&T)!

[TheSmitty]

Here is US I checked this morning and the option is now gone as expected. So, having said that is there away to accomplish what is needed (Calibre etc) another way such as connecting your kindle to a computer?

[JSWolf]

Originally Posted by TheSmitty

Here is US I checked this morning and the option is now gone as expected. So, having said that is there away to accomplish what is needed (Calibre etc) another way such as connecting your kindle to a computer?

Gone in the UK as well.

[Knightreader]

Disappeared in Germany too.

[Quoth]

Originally Posted by TheSmitty

… So, having said that is there away to accomplish what is needed (Calibre etc) another way such as connecting your kindle to a computer?

Yes. At least right now, though it might stop on Kindles that still get updates.
K3 to PW1 will get azw3 (or old mobi for a very very old titles) for reflowable books.
Later models will get KFX (or maybe old mobi for a very very old titles).
In both cases deDRM of 10.0.9 or later is needed. KFX also needs KFX input plugin.
1A. On later models with Whispernet make sure that is on on the device and enable WiFi. The unread book should appear under a suitable view. A tap downloads it. Wait for completion. My Paperwhite doesn't work with the Send to Device on the Web page, but is the default device.
OR
1B. On earlier devices go to Content Web page and Send to Device and pick the device. On the ereader enable WiFi, or if Cell/mobile still connects* enable that (rare!). Select Sync and Check for Content.

2. Connect eink Kindle to Calibre via USB (new MTP Kindles are tricky).
Select Device instead of library view and add new ebook to library. Switch back to Library view. Eject from Calibre.

[* As of 2025-02-27 works with Mobile/Cell only DXG using EDGE. Press Menu after enableing to see the connection mode]

Edit: I can't test the K3 as the battery has died. But it's updated for azw3.

Models from K3 and later were updated by new firmware after about 2017 to have also AZW3/KF8. Models later than the PW1 were updated to have also KFX. The K1, K2, DX, DXi and DXG maybe don't have enough RAM, because they never
got updates.

Updates here: Kindle E-Reader Software Updates - Amazon Customer Service

mobi, prc, azw = Mobi / KF7, though mobi can be dual mobi that has also azw3 in it. Mostly HTML3. No extra fonts. Only Roman-Latin. Can be DRM free.
azw1 = Topaz format. A mad reflowable scanned with OCR system. Any language? Not sure if RTL is supported.
azw2 = Interactive mobi
azw3 = KF8, more fonts, user fonts, publisher fonts. Similar to epub and usually built from it. Subset of HTML5 + CSS3. Can be DRM free. Images can be colour and are same resolution for everyone.
azw4 = A PDF with Amazon wrapper and encryption.

KFX = A family of document types. The common one is made from an epub. Designed for incremental delivery while reading. Compiled rather than simply compressed. Less like original than azw3, despite "Advanced Typesetting". Images are mono unless for a Colour Kindle. Image size might be changed per device. An app might use azw for KFX files.

Amazon also will resize the publishers image upload if they think it's too big, and/or strip fonts if they think there are too many. Actual epubs from other sellers might be better.

Send to Kindle only accepts NON-Kindle formats and Amazon's conversion can be worse than Calibre's. They also get a copy. It needs an internet connection twice.