Seems like it'll have to be a free-only service for now if I'm interpreting it correctly - it seems like Lightning needs me to have a balance to be able to open a channel, and a channel needs to be open to receive through Lightning. Catch 22. I do have some bitcoin elsewhere but I don't want to send it on chain due to traceability concerns.
Discussion
If you go to the trouble of running your own LN node someone else can open a channel to you.
Actually set one up and I'll happily open that channel for you for free. :) Lots of services will do that for a fee too.
Though the software stack to actually receive LN payments via LNURL for nostr is kinda complex right now. Notice how I personally just send nostr payments to my stacker.news account.