Can ‘I tickled his foot excitedly’ mean I tickled his foot so I made him excited? I want to use ‘interestedly’ instead of ‘interestingly.’
No, it can't.
The adverb "excitedly" modifies the verb "tickled." Since the subject "I" is who is performing the action, it describes the manner in which the subject "I" performs the action. It certainly doesn't describe the manner in which the owner of the foot responded since the owner of the foot isn't even in the sentence at all, the direct object of the verb being "his foot," not him.
To be clear, if the adverb were to modify how the direct object of the verb responded to the verb's action, it would be the direct object "his foot" being excited, not this him (the owner of "his foot") you refer to in your question but who doesn't actually appear in the sentence itself, just "his foot."
"Excitedly" is an adverb, modifying tickled. Tickling might be done quickly or slowly, roughly or gently, but not excitedly. Excitedly is how one behaves, not how one makes someone else behave. E.G., "I waited excitedly for his return."
As for ‘interestedly’ instead of ‘interestingly,’ where would you use them? Both are valid adverbs, but certainly not for toe tickling.