iOS 12 Beta 8 iPSW for iPad and iPod can be downloaded from here. You do not need any developer account or UDID for this. The direct download links are provided below for iOS 12 Beta 8 iPSW files. You can update your iPad or iPod via itunes and all the instructions and working download links are available on ipadownload.com.
This is the beta firmware of iOS and it is not directly available under iOS update directly on your device.
iOS 12 Beta 8 iPSW Download for iPad and iPod
Make sure to backup your important stuff before installing the update for iPod or iPad.
iPSW Download Links
iPSW Download links for iOS 12 Beta 8 for iPad, iPod are live. Download the file compatible with your phone model. If any link is not working then inform in the comments.
|iPad Air 2||Download|
|iPad Mini 2||Download|
|iPad Mini 3||Download|
|iPad Mini 4||Download|
|iPad 9.7 inch (2017)||Download|
|iPad 9.7 inch (2018)||Download|
|iPad Pro 9.7 inch||Download|
|iPad Pro 12.9 inch (1st Gen)||Download|
|iPad Pro 12.9 inch (2nd Gen)||Download|
|iPad Pro 10.5 inch||Download|
|iPod 6 Touch||Downlad|