For any Aussies heading over to Europe, in particular Germany but it works across Europe including the UK and Switzerland, I came across Fraenk eSIM. It's app based and very easy to sign up for, accepts PayPal, no IBAN needed etc..
PLANS:
€10 15GB data and unlimited calls and text
€15 40GB data and unlimited calls and text
For this month they are running a birthday promo where you (and referer ;) get a bonus 5GB of data per month for as long as you stay with them. It's capped at 15 referrals per code so that's a bonus 75GB!!!
EDIT: The website has no English option and I don't speak a lick of German, it also contains very little detail of the plans. They kind of walk you through the option via the app. I was able to get by using google lens, Aus passport and PayPal. This is a big advantage over other German phone companies that need German bank details and an ID card.
It's prepaid so it's month by month no contract. There is only a €10 and €15 option for 15GB and 40GB + bonus data.
TIP: If you're unable to download the Fraenk app from play store I found it easier to just create another Google account with location set as Germany, clear play store cache and use the new account. Good luck!!
Current using my cheap German eSim in Finland and can confirm it works great. Costs half what you would pay locally ;)
Referral SPAM