Hi,

I haven’t done that but I used (and use) Linux smartphones like the N9 and N900 and because I need modern connectivity and a decent camera I got a used Pixel 5 with Graphene. My wife uses an XperiaXA2 with Sailfish so I know the system quite well.

So to answer you:

• Android Apps mostly work reasonably well under Sailfish, expect difficulties with some banking apps and greater difficulties with apps that require Google Play (there are hacks to get microG installed, by now even somewhat officially supported, but she never asked for me to try that). Generally this will make the transition quite easy as you can continue to use old apps if you avoided google dependency on Android. Use f-droid and Aurora store to install them.
• Expect to miss many things from android and falling back to app support to fill your needs. (e.g. good navigation app), but as that works generally well that is no problem. Over time your will replace some of those, but not all, with native apps.
• Expect many features to just work which under android are a hassle. E.g. caldav sync to nextcloud or full and automated wireless backups via rsync and a script.
• Never expect completely smooth sailing. While there is a constant stream of updates the system never reached the polished state of android. Most bugs can be worked around but are annoying. Example: On the XA2 the android app support sometimes looses internet connectivity. Workaround: Stop app support (there is a gui button for that), disable SIM slot 1, enable SIM slot 1, enable app support. Once you get used to it, its quick. Or the browser does not work with some websites and crashes, but you can just use an android browser.
• Battery life with stopped android app support is amazing, even after years of usage the phone only needs to be charged once every few days. Battery life with app support enabled is still quite good with 1-2 days on moderate use.
• Photo quality is lacking compared to current android standards. This may be better on newer phones like the C2.

Overall I can recommend it if you are willing to read the forums to find the workarounds and willing to make some compromises. She uses it as daily driver for many years and has no desire to replace it yet. The community behind sailfish is awesome and the developers often listen to user desires.