Vijitha Kumara told me to try
PlayOnLinux. Thank you Vijitha.
sudo dnf install playonlinux # Fedora or:-
sudo apt-get install playonlinux # Ubuntu (etc)
Then I had to find the launcher, which on Ubuntu (Mate destkop) is under Applications→Games and on Fedora (also Mate) Applications→Other. Once that is open, click the install instruction and put k‑i‑n‑d‑l‑e in the search box, and click the Kindle icon to install it. There are various warning boxes and it downloads an old version of Wine, Wine‑Mono and MS fonts, and then it works.