I've been using a mix of folding bikes, (shared) e-scooters, and public transport, for a long time by now, and an additional problem of folding bikes is that at best, they're clunky to carry inside metro carriages (except high-end models, which are expensive).

E-scooters are not very easy to carry, either (15+ kgs is not light, and they're relatively long), but they're practical enough to use consistently.