While there might not be a lot of traveling going on right now, portable batteries can still come in handy during power cuts and other situations. One of Anker's 20,000mAh units is now just $30 at Newegg, while the same battery currently goes for $50 at Amazon.
The PowerCore Lite 20000mAh has two USB Type-A ports for charging devices, and you can top up the battery itself using either microUSB or USB Type-C (the Type-C port is input-only). There's also a trickle-charge mode, for lower-power electronics like wireless earbuds.
The main downside is the total lack of quick charging support: the speed is capped at 3 Amps per port. Still, that's probably to be expected with a $30 battery. You can buy it from the link below, and make sure to use code MKTCHQOKJVKM at checkout to get the full discount.