Frontier used to do something like this for free in 2022. I used the link to book a Southwest flight when my Frontier flight was cancelled. Frontier stopped offering this option not long after. Sounds like the new paid option through Hopper will work in a similar way?

FLIGHT ALERT

We're sorry that we've had to cancel your flight 2175 from LAS - Las Vegas, NV to RNO - Reno, NV on January, 06 2022. We apologize for this inconvenience and the impact to your travel plans.

To assist with your travel, we've put together some options:

Option #1 – Up to $200 for travel on another airline
If you prefer, we'll reimburse up to $200 per traveler for travel on another airline within 72 hours.

Here's how it works: To purchase your tickets within the next 24 hours for one-way travel to be completed within 72 hours, please visit https://rebook.tripeasy.com, using your Last Name and Frontier reference # [REDACTED] to login. Then, book and pay for your one-way travel. Within 14 business days, a reimbursement check will be mailed to the address you provide on the payment page of the booking process.

Option #2 – Full credit for your ticket + a $100 Frontier voucher per traveler
If you prefer to travel with Frontier at another time, we'll provide you with full credit for the unused value of your Frontier ticket plus a $100 voucher per traveler valid for future travel with Frontier.

• Your credit will be sent to you within one week, and will be available for use for booking future travel on Frontier for 90 days from the date the credit was issued; your future travel does not need to be completed within 90 days
• Your voucher(s) will be sent to you within one week, and will be valid for redemption for 90 days from the date of issue. Travel does not need to be completed in that time.
• Voucher(s) and credits are valid for one-time use in booking future air travel on Frontier; Voucher(s) are applicable to ticket fare only, and not to taxes or fees