We found 1 Reddit comments about winSIM LTE All 1 GB Allnet Flat. Here are the top ones, ranked by their Reddit score.
> Alternatively, get a SIM card on contract, as these don't need to be activated via PostIdent. It doesn't have to be a 24 month contract, there are 12 month (or even shorter) contracts.
Drillisch has a huge amount of different contracts on amazon all of them can be canceled within a single month.
Caveats are: O2 network meaning bad signal in many areas and if you go over the data cap they can charge you 2€ for 200mb up to three times (although you can disable that 'feature'). Otherwise i didnt have any problems with them.