Magisk (/system/less root) currently passes the SafetyNet checks and it, and it's MagiskManager App, are both FL/OSS and hosted on github [0] as well as pre-built images linked from XDA [1].
I'm using it successfully with LineageOS 14.1 (Android 7.1.2).
Not really - ultimately they're root, Google SafetyNet isn't, it has to run at the application level. Meaning Magisk will always win until remote attestation is enforced. There hasn't been a breaking update since July if I recall correctly and the Magisk developer had it patched in about a day.
I'm using it successfully with LineageOS 14.1 (Android 7.1.2).
[0] https://github.com/topjohnwu
[1] https://forum.xda-developers.com/apps/magisk