I have a hard time believing this. I'll have to look into it, because I do have a spare pixel 6 device I'd like to install Lineage on, but I also want to use it as backup for my BankID.
I use Bank-ID on a 2014 Samsung Galaxy IIIneo running LineageOS as well as on a Galaxy Tab 3, also running LineageOS. I also use it on a Xiaomi Redmi Note 5 running a lobotomised stock distribution. None of these devices have Google services installed, all have root access using Magisk. These devices range from Android 7 (the tablet) to 11 (the Galaxy SIIIneo), i have no data on more recent Android versions.
Pixel 6 supports grapheneOS which is massively superior in all ways, at least in my opinion as someone who has used both lineageOS and grapheneOS for many years