Deal with multiple domains to transfer traffic to your FSB store?

Unless the domain generates traffic, I would not do it.
If you have traffic, then probably random traffic.
It is highly likely that the traffic you would like not to be generated ….

I know that there are people who redirect domains, but they do it in
the 100 or even 1000 and it would probably take a lot
for the purpose that they are trying to accomplish.

If you think the field is worth being seized based on its age, do it.
with the intention of creating a store one day while you are
waiting to do so, then redirect the domain to your current store, otherwise
I do not think you will get much in terms of SEO for redirection.