@whitequark @dngrs @mntmn 800 Mbps data rate is 400 MHz Nyquist bandwidth / 800 Msps minimum. I can't remember if the MIPI clock is half rate or full rate (which would require double the BW).
You can actually run close to Nyquist with upsampling if you are just doing data recovery not SI work. I've decoded 25G NRZ with a 40 Gsps scope before, and on the extreme case 1.25 Gbps 1000Base-X (625 MHz Nyquist bandwidth) with a 2 Gsps scope.