Cost to repair cracked iPad screen, 2018 (6th generation.)

...but when I click "get estimate" it only tells me what the fee would be with applecare,

I've also seen that and have reported it several times to no avail. You need to contact Apple, and they do not participate in these user-to-user forums. As your fellow end users, we cannot quote repair costs that are not published.

Note at the bottom left of that article page you linked that there is a "Helpful?" section:

Click "No" and briefly describe the issue of the Apple-Care-only pricing.

You can establish repair cost in your country/region here:

iPad Repair & Service - Apple Support

A fixed-price repair is typically c.60% of the as new cost of the iPad - and while expensive, is significantly less the ful, cost of a replacement iPad. Consider that the iPad's screen is the single most expensive component of the iPad.

You can use Apple’s mail-in repair service, or you can arrange repair via the Genius Bar at your local Apple Store or Apple Authorised Service Provider (AASP):

Genius Bar Reservation and Apple Support Options - Apple

For practical purposes, Apple usually exchange the iPad for a renewed/refurbished iPad of the same model and specification. The cost of the exchange is the same as would otherwise be charged for repair. When exchanged, the replacement iPad is yours to keep.