Sharing my iPhone contents to this Amazon fire tablet

The Amazon Fire tablet (FireOS) and your iPad (iPadOS) are entirely different Operating Systems. Unless the App Developers has created the same App for both platforms - and you can download and install the App from their respective App Store, you will not be able to achieve your aim.

An App explicitly developed for one platform cannot be natively installed on the other.

I'm not familiar with the Fire, but if it has the ability to import .vcf cards and you've got a Mac then you could try selecting all you Contacts on the Mac, then in the top menu File/Export/Export as vcf. If the Fire can import vcf files then import them. Note that this will not keep the contacts in sync.