Can you teleport outside? Sure.
Is it safe? So long as there's no rain to smudge your diagram it's basically as safe as doing it indoors. And in Lucien's defense there wasn't any rain at all, right up until the last sylabble of the incantation.
Which means this is probably the safest place to talk to a demon.
Lucien scans through the literature on medical advances again, taking notes. And then it's time to go and talk to the demon, again.
"I'm sorry to bother you again but I was wondering if I could trade with you for some items."
Lucien has a list of future medical tech, mostly for reverse engineering purposes though some items are feasible to make and transport from here in large enough quantities on their own (like some vaccines, so long as they come with refrigeration units).
"- though I'd probably find more items I'm interested in given more time."
"What are your reverse-engineering resources? Like, a lot of this stuff is computerized, for one."
"I put the prerequisites I could find further down in the list, here, though I don't think computers made it on to the list. I was thinking of distributing the vaccines directly and then using the profits to reverse engineering the rest. Maybe leak some things to competitors so there's someone independent to work on it after I get accused of witchcraft."
"Where does your door open to? I don't know how many vaccines you'll be able to store - or how you'll convince people to take them -"
"Door open to? My lab has a basement I can store quite a lot in - the vaccines in particular I don't think will take up much room so long as I make the needles and syringes and such myself."
"I think I can get people to take them if I pass it off as a new discovery and use my newspaper to advertise. Which I'm not normally comfortable using my newspaper for but it seems worth it in this case."
"When you open the door it will put you back where you came from. - you know you can't safely re-use needles, right?"
"Where I came from was a flat near Istanbul I rented for the night - I was planning on teleporting to New York instead. Probably I'll need to do multiple trips."
"We sterilize needles I think, does that not work?"
"They accumulate microscopic defects. I mean, it's probably better than not being vaccinated against things, I'll give you that."
"I'm not sure why we don't use reusable ones - might just be the price. I'd rather not wait on driving down the cost of steel production a bunch but maybe I can get it affordably as is. Or if there's a reasonably sized equipment to produce them cheaply I'd take that."
"I can maybe get you a usable model of stuffprinter, though hypodermic needles would be a very weird use case, they're mass produced and for that people in my world summon demons, stuffprinters are for one-offs."
"I think if people found out I was regularly summoning demons to produce needles they would freak out and maybe, I'm not sure, stop using vaccines indefinitely or something."
"Right, I'm just saying, it might be kind of hard to find a model of stuffprinter from my world that will do well at making hypodermic needles, people mostly use them for costume pieces and stuff like that where it's likely that nobody's already summoned a demon, gotten a batch of ten thousand made, and put them on the open market."
"Maybe there's something pre-Revelation that would work? I'm not sure how your economy looked then. Worst case I can use my world's needles until someone figures out how to do better."
"Pre-Revelation had single use hypodermic needles but I don't know anything about how they were made and whatever it was might be hard to get through your door. ...would nasal spray versions be too weird for people?"
"Hm, I could probably sell people on nasal sprays. Might be easiest to be honest - people don't like needles even when they know it's good for them."
"Quite. And some can be taken orally, polio you can do that way. I don't know if anybody's actually reworked things like smallpox that got eradicated early on for non-injection modalities, though."
"We already have the smallpox vaccine, though I'd be happier for it to be easier to scale and export. Uh, do you know what you'll want in return for all this."
"...this is what I would be doing recreationally, more or less. I can't go with you to your world, I've got obligations in the one I came from with the Elves, but it's not like making stuff runs down a limited resource."
Lucien is torn between wanting to take this at face value (it makes perfect sense to him!) and finding it deeply suspicious that the interdimensional demon with a mind affecting aura would be so helpful.
"What sort of obligations to the Elves, if it's not rude of me to ask."
"...I can resurrect them. Only them and orcs, they have special properties that mean the body's all they need, I can't make minds."
Lucien.... Blinks. Several times.
"Umm. Resurrect then with what sort of constraints and costs? Are they sapient?"
"They're sapient. I can do them in seconds, it's just there - were a lot of them - it really really won't work for humans though."