Here are a few tips from my practice (I've been branding, naming and working on strategic communications for over 25 years).

The right domain depends on a couple of key factors:

(1) Who is your audience and what are you wanting them to do? If it's ecommerce, e.g., buymelissa.com or getmelissa.com can potentially make sense (note: I'm using these as examples, not verifying their availability). If it's a way to get them to go to a store, you could even say "hearmelissa.com" because, after all, it is voice-controlled. You also have to consider the benefits -- "Melissa" may be the answer, but the ultimate benefit might be the equivalent of "speedupyourhome.com" (that's way too long and I wouldn't recommend it to a client -- again, it's simply illustrative).

(2) Your brand. Naming has two essential elements: a) linguistic: phonology, memorability, distinctiveness, semantics, etc.; and b) brand-based: embodying the key attributes of the brand; naturalistic and metaphorical value in marketing and advertising campaigns, etc.

So I've give you some examples. I can't give you an a definitive answer because that requires understanding and analysis of the factors described above. It also requires a sensitivity to potential IP (i.e., trademark) issues; domain availability; negotiation of domain prices; and the like. On top of that, I'd have to ask why your product is named Melissa. It's friendly, but a bit of an old-fashioned name. Does that really conjure of advanced home automation? Possibly if friendly automation is what you're about. But if it's efficient or technologically advanced, probably not.

Last, as for the possibility of using extensions other than .com, one fast answer: don't. You lose in SEO; you lose in confusion; you risk IP and trademark issues depending on who is using the .com and why; and it simply isn't needed when there are plenty of killer .coms that you can use.

Should you like to discuss, feel free to contact me.

Regards,
Steve