On ps5, if you open game base it seems you can invite to a co-op, friendly session that way. The controller in the box icon is the one to click on to do so

KanesJailCell_PSN
@KanesJailCell_PSN
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Friends list showing a “you don’t have any friends in your friends list” prompt when attempting to invite to a ranked co-op game. Any way to resolve this?
Friends List glitch
Friends List glitch