If you want to import only ways, you could use osmium to pre-filter just them, which should make import shorter. I don’t know how big it could be however and how long it would take to import it, but it’s a matter of hours probably. Rough estimation would be 21/3=7 GB of data, and I can import 1 GB of data in ~1,5 h on my laptop, so it could be like ~10 h.