Yes, you can view it as a passive form of the sentence You interest me. However, the proper passive form of this sentence is I'm interested by you.
On the other hand, you can say that interested is an adjective and that interested in sb. is an adjective (deverbal) phrase.
So yes, you can view it as a sentence in passive voice, but if you wish, you can view it as a descriptive sentence that says: I'm a person with a specific property: interest in you. Since the proposition has changed and since the "passive" form is more common than the "active" form of this statement, I would be inclined to the latter explanation.
First off, saying to someone that you personally decided to invite them to, say, a party/meeting using the passive voice, to me, seems somewhat ridiculous; besides, you don't normally invite somebody before you have decided to do so.
In situations where only the fact of invite matters (whoever the inviting person(s) may be) and in case the verb decide is a must, you can say:
It has been decided to invite you.
It has been decided that you will/should be invited.
A decision has been made to invite you.*
*(@Jasson Bassford's suggestion, which, for my money, will be the best choice)
As for the second part of your question, the sentence might read:
Inviting you (to the meeting) is being thought of/about.
Two helpful notes:
The verbs that are followed by infinitives can only be used in passive structures beginning with it. (Examples 1 and 2)
Verbs that refer to wanting, liking and similar ideas cannot be usually in passive structures with following infinitives:
Everybody wanted him to be the manager. (BUT NOT: He was wanted to be
the manager.)
We like our stuff to say what they think. (BUT NOT: Our stuff are
liked to say what they think.)
The source:
Michael Swan. Practical English Usage, Third Edition: New International Student's Edition (417.2, 418.6)
Best Answer
Without object, the sentence cannot be made passive.
The idea of making anything in passive is to interchange the subject and object and thus make the sentence more meaningful or to reveal/hide the identity. Consider these reasons for using the passive voice.
Add some object and it'll be possible.