quickest way to get not provided keywords in google analytics?

landing pages are the closest you'll get. in ga4 look at which landing pages got organic traffic, then check those same pages in search console to see what queries they show up for. not exact, but it tells you roughly what brought people in.

You can't, and any tool claiming it can is guessing. Google stopped passing the search term years ago, so GA4 never receives it. The real data lives in Search Console. Link your Search Console property to GA4 (Admin, then product links) and the queries report shows up under acquisition, though you may need to publish it from the library first. It still won't tie a query to a conversion, which is the bit people expect and don't get.