I read an existing post regarding SD cards for FairPhone 4 (not 5).
My question is twofold: 1) What is the maximum read & write speed that FairPhone 5 supports?
2) Which micro sd-cards would you then recommend?
Edit: Even this post for the FP3, yes from 2019, is not conclusive about A2 and whether FairPhone supports A2 Command Queueing: FP3: microSD controller specs (A1 or A2)
I’ve just created the wiki page for FP5 sdcard experiences: ✏ List of compatible micro SD / SDXC cards for FP5
Edit: that post is essentially a copy of the FP4 version and I kept the note about not formatting as internal storage. Of course the FP5 is new and we don’t have first-hand experience to back that warning, yet. IMHO better safe than sorry.
I entered my brief experience with using my SanDisk 1TB card in the prototype FP5 in the first days of September into the List.
As you can read there, (most likely) the automatic first scan of the card by Android’s Media Storage (system app) consumed a lot of energy and time and heated up the device. It seemed that this lengthy process restarted after I had disassembled the FP5 later, although I cannot definitely say if the disassembly or the inevitable reboot triggered this starting anew from scratch. I have reported this to Fairphone Support.
'lil off-topic but Switchroot made a great guide for microSD cards and their capabilities
Worth as buying advice and to submit here for compatibility 
But nobody knows whether fairphone 5 is using UHS-I, UHS-II or even UHS-III speeds?
At least I then know I don’t overspend or underspend on a sd card in terms of read/write performance.
I personally would recommend AT LEAST class A1 because sometimes the IOPS request can be demanding and would slow down the phone unnessecary just because the microSD can’t keep up… Class A2 could be overkill for a regular user IMO except if you thend to install games or similar on the microSD
Good you mention Class A1 and A2 cards.
Background: Since UHS I, II, III (and previously class 2-10) is more useful for constant stream of data like recording video.
While if you are planning to also install apps/games on a SD card, burst rates might be even more important. For that reason the class A (Application Performance Class) rating system was invented. Which also meet certain IOPS criteria on random-reads and random-writes.
A1 at least:
Random Read: 1500 IOPS
Random Write: 500 IOPS
Sustained Sequential Write: 10 megabytes per second
A2 at least:
Random Read: 4000 IOPS
Random Write: 2000 IOPS
Sustained Sequential Write: 10 megabytes per second
EDIT: … But wait there is more to the story (Hi Jeff): A2-class microSD cards offer no better performance for the Raspberry Pi | Jeff Geerling (which mentions that A2 is BS marketing)
And follow-up: Raspberry Pi microSD follow-up, SD Association fools me twice? | Jeff Geerling