So little update:
I have dirty flashed the lineage 16 and it worked i guess - the rom booted and it gave me "pixel os launcher stopped working" and there was nothing i could do with that back then, at least thats what i thought. As a result i made clean install of the rom and same thing happend sadly . The fix is to choose Trebuchet launcher instead of pixel os and everything works great.
To sum up i think that you can dirty flash los 16 but if the same thing happens to you (which i mentioned above) you just have to use trebuchet launcher.
!!!Make sure to install new gapps if you install los 16 update!!!+ probably you have to flash magisk once again but not sure about that.
I flashed LOS 15.1 on 3 different s2 devices and installed GAppps micro package. After updating the devices to LOS 16 by dirty flashing and installing the newest version of OpenGApps micro package, the pixel launcher crashes just like on Lineague's device. @BMWM5V8 is it a problem specifically related to LOS 16? Is there any way to replace a GApps package by a smaller one without having to flash the ROM all over again?
another issue (which was already present when on LOS 15.1) is that after flashing the LOS ROM all devices now have the same MAC adress, so they can't be used at the same time in the same wifi network Is it possible to change the mac adress without root?
I'd be thankful for any advice