Are ZEGJAW Batteries Compatible With DeWalt?

No. ZEGJAW's own listings never mention DeWalt — the compatibility claim they do make is for Makita.

What the listings actually say

Across all 43 ZEGJAW listings in this catalogue, not one mentions DeWalt. 14 of them mention Makita, in the same sentence, on the battery packs and on the tools that ship with them:

【Widely Compatible with ZEGJAW 20 Volt Tools】: Compatible with 20V ZEGJAW & Makita Power Tools and Chargers, including leaf blowers, tillers, lawn mowers, leaf vacuums, pole saws, or hedge trimmers and weed wackers.

So the honest answer to “does ZEGJAW use DeWalt batteries” is no, and to “is ZEGJAW compatible with DeWalt” it is “ZEGJAW does not claim to be”.

Two cautions before you buy an adapter

• “Compatible with Makita” is the seller's claim, not Makita's. It is printed by ZEGJAW on ZEGJAW's own listing. Neither Makita nor DeWalt endorses it.
• Slide-pack shape is not the whole story. A pack that physically clips on can still be rejected by a tool's electronics, and running an unapproved pack usually voids the warranty on both sides.

If you just need power for a ZEGJAW tool

3 of ZEGJAW's 4 standalone 20V battery listings are discontinued, but 20V 1-Pack 4.0Ah Lithium Battery for Snow Shovel and is still sold. The 20V Lithium ion Battery Charger Fast Charge, Use for is listed too.

The practical route to a spare pack is a tool that ships with two of them: 8-Inch Pole Saw & 18-Inch Pole Hedge Trimmer with 2., 20V Cordless Electric Tiller Cultivator, 9-Inch Till, 2-in-1 8'' Pole Saw & 18'' Pole Hedge Trimmer with 2, 8-Inch Cordless Pole Saw for Tree Trimming with 2x3..