Sometimes, it seems, one needs to spend time to ask the question in order to find the answer themselves...

I tried a final search, and it seems that, even though Waffle 3.5.0 is from very recently, it is not upgraded to work with Java 17. Instead, there is a separate depencency called "waffle-jna-jakarta" that works with jakarta instead.

I guess the regular Waffle for javax.servlet is still updated for posterity.

    <dependency>
        <groupId>com.github.waffle</groupId>
        <artifactId>waffle-jna-jakarta</artifactId>
        <version>3.0.0</version>
    </dependency>

was the answer.