Yahoo! does not offer an allowlist, but they do have a program where you can submit your IP addresses for review.  Based on the review, Yahoo! modifies your reputation in their system if appropriate. It is important to note that an IP address reputation modification by Yahoo! does not guarantee inbox placement.

How to submit your IP addresses for review

If you are submitting an existing IP address, are a new sender or have a new IP address, submit an application to start the review process. Yahoo! will contact you once they have reviewed your IP addresses, although they may not share the specifics of their investigation.