Swashbucklers can attack a lone target with Sneak Attack, as long as they have no disadvantages.
You also get an additional way to use your Sneak Attack; you do not need an advantage in the attack roll to use your sneak attack against a creature if you are less than 5 feet away, no other creature is within 5 feet of you and you have no disadvantage in the attack roll. All other rules of Sneak Attack still apply to you.
Inquisitive Rogues can obtain information about a target and use sneak attack against them as well, as long as they have no disadvantages.
In the 3rd level, as a bonus action, you can do a Wisdom check (Insight) against a creature that you can see is not incapacitated, disputed by the Charisma (Disappointment) check of the target. If you succeed, you can use your sneak attack against that target even if you have no advantage in the attack roll, but not if you have a disadvantage.
A player of mine raised a good point, specifically the Swashbucklers say All other Sneak Attack rules still apply to you., which means that you still need to use Finesse / Ranged weapons. The Inquisitive Rogue does not say it. Although I'm pretty sure they still require Finesse / Ranged weapons, I actually wonder if I'm right.
Is there any reason for this difference in wording? Or should we assume that the rest of the Sneak Attack conditions still apply?