Get yourself a good nicotine vape rig. The kind that has a big tank so it’ll last all day and you can use whichever flavoured vape liquid you like best. Switch to that 100% of the time, right away, no exceptions. Don’t worry about how to quit vaping until you’ve gone without smoking for at least a few months.
It’ll be hard, but not nearly as bad as it is if you try to quit both smoking and nicotine at the same time.
It’s the culture of an instance that makes the difference, not which software it runs, but there is often a correlation. Misskey tends to get more people who appreciate cute emoji and comfy vibes.