When will the 17.2.1 software update be available for iPad?

Unknown. 17.2.1 was a fix for iPhone only. Its unclear if it will ever be released for iPad.

Its more morel likely a further update would be released for both.

With that said, how are you trying to sync them? The point update difference should not affect any data transfer or sync.

It should only be an issue if you created a backup with 17.2.1 you want to restore onto the iPad running 17.2

There is a big problem with this for anyone that buys a new iPad and wants to set it up using your iPhone's backup that is made with 17.2.1... You CAN'T do it. The restore says you have to be running the same or newer version on the iPad! Grrrrrr!

I have no choice but to set up my iPad new and install stuff myself instead of using my phone's configuration.

That's a swing and a miss, Apple!