Do not _artificially_ lower a speed limit (people will drive the speed that feels safe) nor _artificially_ make a roadway more dangerous (it will be more dangerous).
Or even better still, build a separated pedestrian way. Skybridges, underground shopping district tunnels, all sorts of engineering solutions exist for isolating pedestrian and vehicle traffic entirely which will maximize safety and in climates with adverse weather encourage year round walking.
The right way to do it is what the Dutch do: https://www.youtube.com/watch?v=bAxRYrpbnuA
It's called "traffic calming".
Oh, and underground pedestrian walkways, skybridges, etc are absolutely horrible long term solutions. If you'd use one of them for extended periods of time, you'd know. They're generally under maintained over the decades, they tend to get dirty and attract homeless people as shelter (I don't want to get into the debate of why homeless people need to use them as shelter), they're for various reason a top target for muggings, they inconvenience the people you should be encouraging (pedestrians) by greatly increasing the distances they have to walk, which means that people will just stop walking when their 500m straight line walk becomes a 1.2km runaround, etc.
Separate pedestrian ways mostly suck. Segragated infra in very bad weather is used, but in most conditions walking at ground level is preferred. In Germany, many Pedestrian Underpasses (often with shops), Overpasses, Skywalks were abandoned in favor of level-crossings, due to accessability concerns, pedestrian dislike, maintainance hassle and the general tendency of them to get unattractive very quickly.
That probably won't work long-term, see for example 55mph state highways that newcomers to the area tend to drive annoyingly slow on.
In rural areas, segregated infra makes a ton of sense. Nobody wants to be near noisy, dangerous cars over 40mph. So they build separate bike and pedestrian paths in rural areas to connect the denser parts of the country without the need to get in a car in between.
Typical urban road... https://i.ytimg.com/vi/XuBdf9jYj7o/maxresdefault.jpg https://bicycledutch.files.wordpress.com/2020/08/cyclelanes0...
Mixed on a slow neighborhood road (30kph is 18mph)... https://coordinates.ce.gatech.edu/sites/default/files/images...
Completely separate bike path... https://bicycledutch.files.wordpress.com/2020/08/cyclelanes0...