Yes, you’re right.
Sailfish OS is a Linux-based operating system from SUSE known for its focus on privacy and unique user interface. LineageOS, on the other hand, is an open-source Android-based operating system that offers extensive customization options and supports a wide range of devices. The choice between the two operating systems often depends on user preferences regarding user interface and privacy features. I prefer LineageOS because it offers more features. But let me say, that Android is built upon the Linux kernel, it’s not accurate to call it a “Linux distribution” in the traditional sense. But it’s linux based.
I have to say, nothing has changed since 2017, when I first used SailfishOS on my Xperia x2a. I’m currently using my old Xperia, but new Android apps are no longer supported. So why would I install SailfishOS on my Xperia 10 V? I did, and I miss basic features. It behaves the same as it did in previous years. Camera, Wi-Fi calling, and sSIM are not supported. For me, these are imported features in SailfishOS. Android apps like MS Teams can be installed with a warning that a Google service is required.
LineageOS is free and open source. You can become root and configure LineageOS however you want. Why should I use SailfishOS? Just because it’s based on OpenUSee Linux?
I consider SailfishOS outdated. Take a look at FeydOS. That’s how I imagine SailfishOS and might switch to SailfishOS in the coming years.
Currently I am happy with lineageOS on my Xperia 10 V. All I need is working.