You can learn to speak Lebanese Arabic without learning to read Arabic, and for a large share of learners that's the right choice. It's a decision worth making deliberately rather than by default, because it affects what you'll be able to do later.
Why the question even arises
Arabic has an unusual split. The written standard — Modern Standard Arabic, fuṣḥā — is the language of news, books, formal speech and education across the Arab world. The spoken varieties people actually grow up with differ from it substantially, and from each other.
Lebanese is one of those spoken varieties, part of the broader Levantine group that also covers Syria, Palestine and Jordan. It has no official written standard, which means there's no single correct way to spell it.
So a learner who wants to talk to their Lebanese family isn't choosing between reading and speaking the same language. Those are two fairly different undertakings.
What skipping the script costs you
You won't be able to read signs, menus, messages in Arabic script, or anything written. You'll be reliant on whichever transliteration system your materials use. And if you later want MSA, you'll be starting the script from scratch.
What it buys you
Speed, mainly, and a lot of it.
The Arabic script is learnable in a few weeks, but reading fluently takes considerably longer — short vowels usually aren't written, so accurate reading depends on already knowing the words. For a learner whose goal is conversation, months spent on reading are months not spent speaking.
How people write Lebanese anyway
Two systems in practice.
Academic transliteration, with dots and marks under letters, used in textbooks. Precise and slow to read.
The chat alphabet, used by Lebanese people themselves in messages for decades — Latin letters with digits standing in for sounds English doesn't have. It's informal, it varies between writers, and it's what you'll encounter in real messages from real people. Learning to read it is genuinely useful for anyone communicating with Lebanese friends or family.
Note for Sally: two or three examples of the chat alphabet here — the common digit-for-sound substitutions and a short phrase written both ways — would make this section concrete. Please add in your own spelling.
Who should skip the script
If your goal is talking to family, a partner's family, or people in Lebanon — skip it, at least at first. Get speaking, add the script later if you want it.
Who shouldn't
If you want to read Arabic literature or news, work professionally with Arabic documents, study the language formally, or learn MSA alongside the dialect, start the script early. It's much easier to learn alongside the language than bolted on afterwards.
The middle route
Plenty of learners do spoken Lebanese first and add the script after a year, once conversation is comfortable. By then you know the words, which makes reading them considerably easier than it would have been at the start.