Have you tried using Magisk hide & MagiskHide Props Config to enabled SafetyNet? If SafetyNet is enabled then Google Pay, other Payments & Bank apps might work just fine with MicroG (I haven't tested it, just a theory).
MagiskHide covers up the fact that your system is modified. When they talk about "somehow retain[ing]... privacy" it's more about telemetry built into the apps themselves.
It's a statement on Chrome, Maps, etc. tracking you when you use them, which is distinct from whether or not specific ones have SafetyNet-induced breakage.
Google Pay won't work even if SafetyNet passes because it depends on Google Play Services APIs that aren't implemented as part opf MicroG.
I haven't had any issues with any of my banking apps despite SafetyNet failing. They don't like root but they don't seem to care about SafetyNet.