Only for a little bit with 〜だけ
Grammar Explanation: Limiting with 〜だけ

While waiting for his brother, Akatsuki finds Akari. He decides to pass the time by having Akari give him a tour of the area, but she explains that as a trainee she can’t take on customers by herself.
Akatsuki hops into Akari’s gondola, saying it’s okay as long as he’s not a customer; he’s a friend.
- 灯里:
- 「本当
( にちょっとだけですよー」- “It's really just a little bit!”
Akari is limiting the the gondola tour to 「ちょっと」, a little bit.
Key Points
だけ limits the amount
だけ marks a limit, so Akari means “only” or “just” this much.
Here it narrows the gondola ride to a very small amount of time.
ちょっとだけ is a common set phrase
ちょっとだけ means “just a little bit” and is very common in everyday speech.
Akari is reassuring him that the favor will be brief.
Sentence-final よ adds emphasis
The よー ending makes the reassurance sound emphatic.
It is not new information so much as an insistence on the limit she is setting.