The existing chargers for these cars are much slower than the slower Tesla chargers, so it's not like these cars will face an overall worse experience.
No, these cars charge at maximum 240kW when the voltage is sufficient. But on a Tesla charger without sufficient voltage they charge at 100kW. Therefore the experience is significantly worse.
This is only true for somewhat old and obsolete Tesla superchargers, like V1 and V2. Since the introduction of Supercharger V3 they're all 400-1000V, so any car, with any internal voltage can charge at their rated speeds.
I believe you've mixed up the versions. That's only true for Supercharger V4, not V3. V3 did not support high voltages. V1 and V2 did not speak the CCS protocol so they were even more obsolete.
