I'm not entirely sure if this fully answers your question or if it's still accurate, but I came across a graphic comparison a while ago that illustrates how Apple Pay and Google Pay handle payment tokens. According to this infographic, it can be assumed that Apple does not pass every payment through their own servers. As a result, even if they do store some information, it's likely not much.

On their website they state

Apple Pay is also designed to protect your personal information. Apple doesn’t store or have access to the original credit, debit, or prepaid card numbers that you use with Apple Pay. And when you use Apple Pay with credit, debit, or prepaid cards, Apple doesn't retain any transaction information that can be tied back to you. Your transactions stay between you, the merchant or developer, and your bank or card issuer.

That sounds to me as if they collect everything they can and then anonymize it. So like with everything Apple you just have to trust them. If that’s enough for you, go ahead and use ApplePay.

I would avoid using an employer supplied device for personal use! More often than not these devices are "managed devices" which consists of management profiles that could grant all sorts of permissions from normal diagnostics, restrictions to location, camera and more!

With that said Apple in such case would become the middle man in relatio to the transaction! That means that Apple pay would retain the purchase logs on your card and ~~send a apple.com description to your bank~~ to mask all your purchases! In theory you'd be given more privacy in relation to your bank but you'd be introducing a third party in the process and more potential failure points!