The portions of SailfishOS specific to it including the user interface and application layer are nearly entirely closed source, unlike the open source Android Open Source Project (AOSP). SailfishOS has far worse privacy, security, functionality and usability than the Android Open Source Project. It isn't possible to make a fork improving it due to it not being open source like AOSP.

You can run desktop apps on GrapheneOS including on a desktop monitor via the desktop mode with free form windows. There's support for non-native apps via hardware-based virtualization. These features are experimental but already work pretty well.

There's a new Jolla Phone in pre-marketing phase right now (almost 9000 phones have been pre-ordered so far). First device deliveries are scheduled for this summer and this should easily be the new benchmark for officially supported SailfishOS devices.

The situation with Sony Xperia devices is not great, the best experience is still on the X10III (from 2021 I think) and there are significant issues with the support of 10 IV and V generation devices (a free beta release is available for those as well).

It seems that recently there has been quite a lot of buzz in the Sailfish community compared to the past few years. In the public repos there are some interesting contributions like xdg-shell support for Lipstick, which looks set to enable compiling many previously unavailable Linux apps natively if that will actually be integrated in an upcoming OS version.

They have been underfunded for a decade now, with some unfortunate consequences - the web browser is based on Gecko 91.

Jolla mishandled the funds they got for the tablets, it went bankrupt and bought up by a company connected to the Russian state. Jolla lied a lot during these events and tried to hide what happened, and I don't think that's an acceptable thing to do when the main selling point of your product is privacy and trust. AFAIK they recently got bankrupted again and bought by the original owners, but it's hard to rebuild trust.