If I were the Panthers, Lance wouldn't be on my radar at that price at all. I also think 1.9 is probably too high for Richardson, who has a lot of upside, but a long way to go (I do think that might be what Carolina does though) but if they land a really good offensive coach, maybe it could work.
I don't think I'd want to trade 2 1sts and 2 2nds for the right to pay Lamar 300 million. Personally, I think the Watson and Wilson trades both look awful right now, and they weren't coming off 2 straight injury plagued seasons, lower body specifically. Lamar is an above average QB, but his game probably isn't going to age great. 5 years from now, I think there is a good chance Lamar isn't in the NFL anymore. That said, the NFC South is pretty wide open, so adding Lamar would instantly make them the division favorites. I kinda think Lamar would make more sense in Atlanta, where they already have a run heavy scheme, solid OL, 2 good young pass catching weapons, and most of importantly, a HC on the hot seat.
I would 100% give up that package for Bryce Young, who I'm a huge fan of. That said, as a Bears fan, I don't know if that is enough for the 1.1.
Ranking those options for Carolina, I'd say:
1. Young
2. Richardson
3. Lamar
4. Lance