Do spirits need bodies to manifest? Every instance in the Bible where a spirit, (including for the most part God) speaks to a physical person, or moves a physical someone it is done in a body or through another person that possesses a physical body. Is it necessary for a spirit to have a body to manifest?
As a lifelong Protestant whom most people accept as being 'evangelical' I would say the following :
There are many examples and this is but one [Acts 8:27-29, KJV] :

Behold, a man of Ethiopia, an eunuch of great authority under Candace queen of the Ethiopians, who had the charge of all her treasure, and had come to Jerusalem for to worship, was returning, and sitting in his chariot read Esaias the prophet.
Then the Spirit said unto Philip, Go near, and join thyself to this chariot.

Here we see God, the Holy Spirit, communicate directly to Philip, in spirit, without any physical intervention, without any other agency and without any manifestation.

From the OP's comments I would suggest it may be helpful to consider I Theesalonians 4:14 :

For if we believe that Jesus died and rose again, even so them also which sleep in Jesus will God bring with him.[KJV]

Human minds are immaterial but require the material presence of a brain in order to communicate intelligently and logically. The question of whether a human spirit can 'communicate' without a brain or by by-passing the brain is somewhat hypothetical.
Disembodied human spirits 'sleep'. And the question of 'communication' then becomes totally hypothetical. If we die in the Lord, we shall experience whatever that 'sleep' is.
The disembodied spirit of the rich man (who did not help the beggar Lazarus) 'communicated' with Abraham (perhaps) or possibly experienced something within himself, in hades, which Jesus attributes to a likeness of communication with Abraham.
Myself, I do not think we have sufficient information in scripture to answer the question. As I say, we may experience something in the future, if the Lord tarries.
It is an interesting question, however, and I did up-vote it.
We are what we are. And what we are, is what God made us to be. And we can only express ourselves (in prayer, particularly, as the OP comments) in spirit and in understanding with a human spirit and with a human mind.
Yet, if we receive and believe the Gospel and are justified by faith we shall receive the Holy Spirit in a union of spirit, within our own spirit. Then shall we pray in the Spirit and with our own understanding.

What is it then? I will pray with the spirit, and I will pray with the understanding also: I will sing with the spirit, and I will sing with the understanding also. I Corinthians 14:15, KJV.]