The phrase "as a friendly gesture" is correct and can be used in written English. You can use it to describe a friendly, kind act that someone did. For example, "He opened the door for me as a friendly gesture.".
Doing this as a friendly gesture in the neighborhood could backfire".
The offer is seen as a friendly gesture highlighting warming ties between the former adversaries.
As a friendly gesture, Mary triumphantly drags out a coffee table as a gift.
Colin Dexter's Inspector Morse whodunnits occasionally refer to the sleuth's earlier cases, but only as a friendly gesture to fans.
Whether you propose a trip to the movies or offer to cook her dinner, she might misinterpret your question as just a friendly gesture.
It struck many who know of this deal as something more of a friendly gesture than an investment made with an eye toward big returns.
No, Kevin, this is not a friendly gesture that says, "You make me feel as comfortable as a turtleneck sweater".
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