@gritnot you can get the pinephone, it supports a few great gnu systems if you are good with Linux. There aren't really any Samsung phones that you can use for custom systems unless they are old so you are better off with the oneplus phones or better yet the pixel phones for lineageos. But lineage is not that great from alot of viewpoints from other testers. There is however grapheneos which I think split off to a managed service of copperOS, which is a heavy security oriented os.