This is a bit niche, but for anyone going to Europe this summer, and traveling to / through the Netherlands, Vodafone NL is offering a ripper deal on their prepaid data bundles until beginning September.
Prices are in the link, most appealing of course is the 1 week option which gives you unlimited data throughout EU for 7 €, this works out to a very competitive ~ 30 € / month.
There are one or two options priced at the same level eg Lyca mobile NL, but based on my experience travelling Europe for the past month in NL, Greece, and Italy, Vodafone is much more reliable and one of the best options for roaming throughout EU. At this price it is a steal.
As far as I know you need to get a physical SIM in the Netherlands to access this deal.
And for the skeptical, just like PwC Australia is not representative of PwC global (or is it? …) Vodafone is a different beast in Europe compared to Australia. Good speeds and good coverage.
This offer is far, far cheaper than travel sim offers (such as https://www.ozbargain.com.au/node/784784), with the caveat of having to be in the Netherlands to sign up.
Terms and conditions: https://act.vodafone.nl/zomerbundels/Voorwaarden-Prepaid-Unl…
I don’t know if still available but orange Poland is free for 1 month and lots of data.