Twitter DMs are such a great resource. Go sign up for a tool like BuzzSumo (they got a free trial) and use their Twitter influencers search feature to find user

Twitter DMs are such a great resource. Go sign up for a tool like BuzzSumo (they got a free trial) and use their Twitter influencers search feature to find users that have a specific keyword in their bio. Then DM the ones that have DM public, and ask for their opinion. Or alternatively, just send them a regular message, without trying to spam.