Hey Aidan! Super late on this, but you have two options if you want to attach the relative to the verb. Using your example with food, we could say either "chakula ninachopenda," or "chakula nipendacho."
In terms of meaning, there really isn't much of a difference. That said, since "nipendacho" is technically tenseless, it can often be used to imply habitual behavior. So, if you're having dinner and want to tell a friend that you always enjoy ndizi, you could use "chakula nipendacho ni ndizi" to make it clear that you just enjoy bananas in general. If you particularly like the bananas at this dinner, though, you might go for "ninachopenda," and then maybe modify it with something like "Kwa kawaida napendelea maembe, lakini chakula ninachopenda zaidi mlo huu ni ndizi," to make the meaning clear.
Also, since "nipendacho" lacks tense, it can only be used to imply present or habitual meaning. If you wanted to attach a relative to the verb in the present or future, you would have to use the inserted form. So you could only use "Chakula nilichopenda" or "Chakula nitakachopenda," with the 'ka" being a necessary add-on that doesn't really carry any meaning on its own.
As for your use of the object infix "ki" here, you can only do so by using the "amba-" relative. It has to be "Chakula ambacho nakipenda/ninakipenda."
In case you're skeptical, I was certified at an advanced-high level after living in Tanzania for nearly seven months, and I breezed through all of my grammar classes while building that fluency.
Hope this helped! Let me know if you have any other questions or want some conversation practice. I always love helping out other people picking up Swahili.