Most car trips could be replaced with ebike trips, but the majority of distance travelled (and thus, roughly, carbon emitted) can't. 80% of the distance driven is with trips >10 km, 70% of the distance driven already at >20 km. There are people doing these trips on E-Bikes daily, but even with great infrastructure they'll remain a small proportion of the modal split (Data from Germany, MiD, 2017). The long(er) trips are the majority of the problem, as the rest are, well, short.
Most rail should be powered by overhead electricity, but for short- to medium-term gains BEMUs are also great, with most European train manufacturers not building DMUs anymore. They'll hopefully also come down in price, as this first generation is really expensive.
I know that the US (and Canada) has issues with battery busses, but in (western) Europe, they work great (but currently still a tad too expensive). Trolley busses are even more expensive (similar if not higher purchasing cost, much higher infrastructure cost, slightly less energy usage) and require a whole lengthy political process to deploy, while battery busses can be deployed in a few months.
BEVs are the only feasible solution for replacing a large part, if not most, of the emissions from cars. Even in countries with a great countrywide transit network and reasonable bike infrastructure (Germany), 73% of passenger-kilometers are traveled by car (MiD 2023, 19% by transit, 4% by bike, 4% by walking), down from 80% in 2002. There is no way to much more than double transit usage in the next 15-20 years. And the situation is much worse in e.g. the USA where little good transit exists, where good infrastructure exists operations suck, building transit is astoundingly expensive, land developmental patterns run contra feasible attractive transit and transit agencies seem unable to learn anything from outside the US (in operations, construction, planning, ...).
This is not to say that anti-car policies (and pro-walking/biking/transit) policies shouldn't be implemented and are in many cases preferable compared to subsidizing BEVs, but their potential in the short- to medium-term for carbon reduction is quite limited.