Oukitel has launched its first-gen P2001 Portable Power Station as a reward via the OEM's latest crowdfunding campaign. This device is rated for a 2,000 watt-hour (Wh) capacity, and offers a range of outputs, AC and USB type C ports included, for an off-the-grid electricity at need. Oukitel claims that it can charge both mobile devices and home appliances several times over on a single charge.
https://www.notebookcheck.net/Oukitel-debuts-its-first-ever-Portable-Power-Station-on-Kickstarter.593260.0.html
Saturated market... There are tons of these already.