My knowledge about biking infrastructure is lacking but doesn't it make sense to allow/promote biking on the sidewalks as a start? Once biking gains more acceptance, allocating more budget for proper biking lanes would become much easier.
When I'm on a sidewalk with my bike and there are pedestrians around, I hop off and walk.
My city has some master plan for bike infra, but really it's a matter of waiting until a road or intersection has to be rebuilt (frequently due to hard winters) and thinking about bike traffic at that point. There's also a network of sleepy neighborhood streets that are used by cyclists including myself.
Maintenance is also a big problem: a sidewalk which is cracked or full of snow / puddles is unpleasant even if it's relatively safe to ride through. One indicator you can use are the number of people riding motorized wheelchairs on the road shoulders — we generally have decent sidewalks here in DC but a lot of the neighboring suburbs added bike lanes during the pandemic and every time that happens you'll notice a ton of people using wheelchairs and strollers there because it's so much better than bumping around over broken concrete and dealing with random poles in the middle of the sidewalk.
The single most important thing which needs to happen is thinking about connectivity: what a lot of places do is make a couple of bike lanes which don't connect places people live/work/shop and then say nobody's using them without recognizing that the miles of unsafe streets on either end are probably the explanation.
I think one issue is that motorists notice bikes on the road or bike lane more than they notice bikes on sidewalks, hence more likely to hit them when turning. But I agree it's a way to bootstrap up.