I am looking to buy a used fairphone in Belgium (or anywhere shipping within EU). The newer the better so it lasts longer. I am considering fp4, 5 or 6 depending on the price. The price of refurbished fp6 in all the refurbished web shops I found is higher than the price of the new fairphone 6 in the manufacturer web shop
You don’t say what you’re wanting to achieve, but I saw today that Amazon UK are offering new FP4 (model F4FPHN-1DG-EU1) shipping from the EU for £271 (GBP) so the price in Belgium is likely to be comparable. This will ship with Android 11 (A11), but you can upgrade to Fairphone’s A15. Other 3rd party ROMs are available.
Regarding A16, my impression is that forum participants don’t expect Fairphone to produce A16 for the FP4, but I don’t recall seeing an official announcement to that effect. I (and I dare say you) would welcome any light other forum participants can throw on this.
I would expect the FP5 and FP6 to receive A16 in 2026 but beyond that only time will tell.
Regarding the FP4, the FP Support site states “Software: Android 15, updates until 2028, …Spare parts available until at least 2028“. Those software updates will likely be the Android Security Update, probably every 2 months.