iPad Air 4 USB-C Pendrive Format exFAT is not showing up

FAT (a.k.a. FAT16), FAT32 and exFAT (a.k.a. FAT64) are a universal filesystem format - although the cluster size can be defined/altered during device formatting.

Some computing devices are sensitive to cluster size - and may have difficulty accessing “unexpected” cluster formatting.

Requirement to format devices using a Mac, for use with iPad or iPhone, is a myth - although you are always welcome to try anything that may work for you. You can use almost any computer OS to format a drive to one of the FAT standards, be it Apple, Windows, Linux etc. (NB: notable exceptions to devices that have capability to format external filesystems are iPad and iPhone!).

If you are having difficulties formatting your flash memory device, first ensure that you are using the “default” cluster size; for windows, you can easily select the formatting options using both the UI and Command Line tools.

Additional information for Windows can be found here:

https://support.microsoft.com/en-us/topic/default-cluster-size-for-ntfs-fat-and-exfat-9772e6f1-e31a-00d7-e18f-73169155af95

Was this drive formatted with a Mac or a Windows PC?

External drives that are going to be used by an Apple iOS device need to be formatted/re-formatted using a Mac.

Formatting external drives for use with an iPad needs to be formatted using a Mac is NOT a myth and was mentioned somewhere in Apple's documentation for formatting external drives to be used with iOS devices running iOS/iPadOS 13 and later.

It is late and I am too tired and lazy to find/hunt down this info for you, but it exists and is where I got that info!

If you do not believe me, search the Apple Website, yourself, for use of external drives with iOS devices.

I believe it was mentioned in one of Apple's infamous tiny footnotes on formatiing external drives for use with iOS devices ob iOS/iPadOS 13 and later, but I do not exactly remember.

Apple DID mention this requirement.

I didn't make it up!

No argument is necessary. Whilst I am genuinely and sincerely curious as to your source, your conviction is based upon incorrect information.

If you can identify the source, if derived from an Apple KB page, we can endeavour to have it corrected with accurate and appropriate information.

The need for an Apple computer, to format external storage devices, is limited to APFS or HFS proprietary formats. This limitation does not apply to FAT.