Here's my write-up from last year about the Dutch Vodafone SIM I bought on eBay. Most of this is still valid. Still available from the same seller I got mine from last year on eBay - "cheapeusims" - search ebay for "vodafone YOU sim" and they are the first result.
https://community.ricksteves.com/travel-forum/tech-tips/dutch-vodafone-sim-card-for-use-in-europe
Changes since last year: you now get 2X the amount of data in a 30 day "You" bundle for the old prices. So...for 10 euros you get 2GB instead of only 1GB, for 20 euros you get 6GB instead of only 3GB, valid for 30 days. I use about 100MB to 120MB per day when travel, using Google Maps extensively when exploring cities and towns but not streaming video on the SIM.
Also, Vodafone SIM credit good for only six months now, not a year anymore. You need add credit or buy a bundle to keep the SIM active or it will be deactivated (probably) after six months of inactivity, once you have activated it.
Also, some people have reported needing to set the Access Point Name (APN) to get mobile data to work. I didn't need to on any of my Android phones - I've used it on several. Last used the card this last May in Portugal.
I recently received a report that someone could not access her Gmail while using the SIM due to Google complaining about the SIM. Personally, I use "2 factor authentication" with Google (they text you a code for each new Google or Gmail login, making it a little harder for someone to hack you), and Google has never given me an issue with Gmail using this SIM anywhere.