The Sailfish "Kvarken" 4.1 spin for the Sony Xperia 10 II is their first with a "fully stacked" 64-bit ARM Sailfish OS image.
As for the very long time for Jolla to embrace 64-bit Arm, they noted in the 4.1 announcement, " Community has been enquiring Jolla about going 64-bit since its early days. While we appreciated the push, there hasn’t been a pressing case to do the switch, and we kept on supporting a nicely working 32+64-bit architecture sandwich throughout our devices, even after the new CPUs, SoCs, and the Android itself had turned 64-bit. The benefits that a 64-bit Sailfish OS would bring are not immediately tangible: the quickest gain is being able to install and run 64-bit APKs via our Android App Support. Websites such as ApkPure started offering 64-bit APKs by default, and that introduced an extra burden to the users of 32-bit Sailfish OS. 64-bit however makes us future-proof, where we’ll be able to address devices with larger RAM sizes, and support complex graphics (such as augmented reality and face ID). From the technical side, no longer being 32-bit eases our porting process to the 64-bit Android base, and automatically prevents issues that we otherwise had to work around in the past. 64-bit is no easy feat when your Linux stack is still 32-bit. And when the push came to shove, we turned our heads towards the Sailfish Core, which was the first to be converted. "
Sailfish 4.1 also updates its Android app support compatibility to the Android 10 API level.
Sailfish 4.1 also has various app improvements, an Open Forti VPN plug-n for Fortinet virtual private networks, the ability to install new search engines for the Browser, and a number of fixes.
More details on this 4.1 update via the Jolla blog .