Who said he is doing it for fun on his free time? The device would be branded Livermorium Ltd, that's a company for profit, not a hobby. Companies with a good record who can claim a stand at the MWC in Barcelona, as well as recent positive media coverage like the Moto Mod mentioned in several big tech media, certainly have some capital and some credibility to attract additional investments.

This community here on TMO has long asked for a HWKB device, "we" even built our own as part of the TOH system thanks to Dirkvl and Kimmoli's efforts. Now, the GPD and the Gemini have clearly demonstrated that the market share for a high end HWKB handheld device could be big enough to be economically realistic. This might not be the most lucrative idea ever, but I would say it is at least very timely now that GPD and Gemini have re-ignited the love for HWKB handheld devices and drew attention on such projects, to the point that they are no longer seen as just hobbyist jokes. Maybe it was enough to attract third-party investments, or to be competitive in tech open calls, but at least it seems that Chen has been successful in fundraising for developing (and producing? No idea) his device without a crowdfunding campaign. I don't see why being so skeptical while no one is asked to pay anything before the device is demonstrated.

Also, I really doubt that Jolla has invested a penny in Chen's project, but this informal meeting with Cybette, as well as the teaser at the end of her tweet, tend to make me think that Jolla is not taking Chen as a scammer: