There is definitely overlap between the 5e Warlock and the PF2 Warlock. It is certainly not perfect, but it is workable. (The playtest version of the PF2 Witch will also be available in October.) There are bloodlines that correspond fairly closely with the available Warlock patrons: GOO (Aberrant), Archfey (Fey, Hag), Fiend (Diabolic, Demonic), Undying (Undead), and Celestial (Angelic).
It might be easier to just add the depth you want to your 5e game. There are lots of resources on these forums, UA reddit, and the DMsGuild to help with that task.
Not to me. It would be much more difficult for me and my group to completely switch systems. We introduce house rules all the time, so we can do that on the fly. But make a change from 5e to PF2e, that would be a hard stop reboot I would think.Well... It is just much more work, right?
Yes, my mistake. I meant that the PF2 Sorcerer can work for the 5e Warlock. They could take Sorcerer (Undead Bloodline) with the Fighter dedication archetype. They will not get armor proficiencies, but armor proficiency in itself does not have the same weight in PF2 as it does in 5e. When they eventually open up Champion options for Neutral and Evil alignments, that would probably be a good choice for your player, since they could declare Vecna as their deity while picking up armor proficiencies.I assume you mean Sorcerer per the bloodlines, right? I thought that too. He is currently a Fighter 1/Warlock 5, and his patron is Vecna (don't ask). I think the Undying Sorc with a Fighter Archetype might work.
I probably will try to play some PF2 but 5E will remain my main game. I still really want something in between 5E and Pathfinder but I don't think PF2 is quite how I'd envisioned it. I really love the three-action system, though.