If that is matter of assistant as OpenAI it defines as a service it is AFAIK impossible, for now anyway.
But if it is meaning ”digital assistant that works as a chatbot doing various things” then there is those two options.
I’m using both of them. These are a bit different solutions aiming different targets and I would say even both have some pros and cons using both gives result where 1+1 is more than 2.
So… I’m heading toward off topic, again, but I really hope that even those two are competive products you guys can be that much co-operative that you can avoid technical conflicts.