Prepositional phrase Vs Direct object

I have seen the rule put forward that

We need a direct object to form a passive sentence.

The following sentences don't have direct objects according to some schools of thought, they have prepositional phrases. But are these sentences passivisible?

He is playing with me ["with me"= prepositional phrase] no direct object in this sentence

John is sitting by me ["by me"= prepositional phrase] no DO in this sentence

I slept in the bed ["in the bed"= prepositional phrase] no DO in this sentence

Mary arrived at school ["at school"= prepositional phrase] no DO in this sentence

He fell on the ground ["on the ground"= prepositional phrase] no DO in this sentence

There are questions I feel can't be asked in isolation:

Can a prepositional phrase like these act like a direct object?

Should it be called a direct object?

Are there exceptional cases?

How does all this bear upon passivisability?

I will be very grateful to you If you provide the reasonable answers of my questions. Thank you so much!

The premise of the question, namely that "we need a direct object to form a passive sentence" is not correct. Active sentences with prepositional phrases can indeed be converted into passives, such as in the first example:

I am being played with (by him).

Google shows plenty of hits with the similar phrase "You are being toyed with".

In fact, all of the sentences listed can, in an exercise in syntax, be converted to the passive as follows:

I am being sat by by him

The bed was slept in by me

School was arrived at by Mary

The ground was fallen on by him

Whether such constructions are considered acceptable has a lot to do with why we use the passive in the first place. Clearly, the passive allows the speaker or writer to make a certain person or thing the subject of the discourse.

So, the active sentence:

The decorators arrived at the school shortly before dawn

could in theory be converted to:

The school was arrived at by the decorators shortly before dawn, and by late evening had been completely repainted

if we wish to make the school our focus, not the decorators.

No doubt the passive here would still be found questionable by some. And this may also have something to do with the greater acceptability of idiomatic verb + prepositional phrases in the passive. Compare the following two sentences:

The room has been gone into many times today.

This problem has been gone into many times.

The second sentence with its idiomatic use seems much more acceptable.