You can get a pass till July 2025 by creating/setting a registry key that they made for businesses.
Paste this in a .reg file and double click it.
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome]
"ExtensionManifestV2Availability"=dword:00000002
Article says you cannot side load books on Apple Books. That is incorrect. You just send an epub to books via the share menu on Mac or iOS and it loads it. Also syncs it via iCloud if you want it to.
Perhaps the author meant you cannot download purchased books off of Apple Books.