TL;DR- I don't think its a scam, the npubs just need to be honest.

I don't think its a scam just to offer sponsorships, and they seem to be (quite publically) actively posting and troubleshooting and reaching out to clients to address issues. I darn sure was not offered a 250k mountain of sats but I let them zap a few thousand to fund my rizful wallet and told them I would try them out and be honest with any issues. While I haven't had any issues sending or receiving zaps, It's not quite as good as using primal wallet in the primal app but once they get it to sync zap messages with PFP on the tx history it'll be good.