I'm new to this also, but asking an LLM it said this:

No, you do not need a Lightning channel open to receive a BOLT12 offer payment¹[1]²[2]³[3]. BOLT12, also known as Offers, is a new payment protocol for the Lightning Network that offers enhanced privacy, reusable payment codes, refunds, and more¹[1].

Here's how it works:

1. A merchant publishes an offer, such as on a web page or a QR code⁴[4].

2. The user scans the offer and sends an invoice request to the intended recipient over the Lightning Network¹[1]⁵[5].

3. The recipient replies with an invoice containing a unique payment hash¹[1].

This process happens without a dedicated server, thanks to a technology called onion messages¹[1]. Onion messages are very similar to onion payments, but they're more efficient and don't require locking any liquidity²[2]. Importantly, channel liquidity—or channels, for that matter—aren't even required¹[1]. So, you can receive a BOLT12 offer payment without having a Lightning channel open.

Source: Conversation with Bing, 5/1/2024