I haven't seen a microSD card that did not work, but I have not seen any anyone testing bigger that 32GB cards.
Cards should be FAT formatted and only DOS-style 8.3 filenames are supported. Longer filenames always have an abbreviated name.
For performance, there is huge speed difference between cards, and most important, the speed rating is hardly relevant.
The speed rating (Class-4, Class-5, Class-10, UHS-I, UHS-II) are marketing numbers and characterize performance for long contiguous read and write operations. While in Axoloti small buffer read and writes are far more relevant.
I have seen Class-4 cards perform well, and I have seen UHS-I cards perform less stellar.
The UHS-I and UHS-II specs are not used, but those cards are backwards compatible.
This site has some detailed benchmarks, most relevant are the "Random Read, 4 KB (QD=1)" and "Random Write, 4 KB (QD=1)"
The "sdbenchmark" object in Axoloti runs similar benchmarks also including smaller buffer sizes. Put it in an empty patch, launch the patch, and it will print the results in the log.