Pilot reported a near complete avionics failure in flight. Pilot diverted and made a descent in VMC to landing.

Narrative

While cruising at 17000 ft. IFR and above a layer at about 16500-17000; I experienced a near total avionics failure with no notice and only one potential leading indicator. Initially; my GTN650 reported a loss of BARO VNAV. Within about 30 seconds; and prior to any troubleshooting; an apparent power surge caused the unrecoverable loss of both ADAHRs (Air Data and Altitude Heading Reference System) boxes; my engine data monitor; and both primary flight displays. While the displays regained power; none of the modules reset; leaving me with no flight indications. The GTN650 remained operable (although without the BARALT (Barometric Altimeter feed). I [advised ATC]; proceeded east until I could make a VMC descent; then proceeded directly to ZZZ; using the GNT650 and ForeFlight for position and GPS altitude guidance. I landed safely using visual reference to estimate airspeed; canard type aircraft are extremely stall resistant. Shutdown and subsequent restart cleared the obvious errors. However; the BARO VNAV failure remained. I proceeded VFR to my ultimate destination. Goods: Decision to immediately [advise ATC]. Decision to remain VMC instead of making an unreferenced descent. Use of backup paper checklist in lieu of failed electronic checklist. Effective engine management despite loss of all engine indications. Others: Failure to anticipate mode of failure and create a checklist. Failure to timely realize how to completely de-energize the ADAHRS/EDM modules without removing aircraft power (which would have induced engine stoppage due to dual electronic ignitions). Failure to incorporate an emergency ignition battery test into routine maintenance schedule; leading to the decision to keep main power on to avoid risking an engine stoppage. Failure to realize the loss of BARO VNAV implied a loss of Mode C (and ADS-B altitude) until subsequent flight.