What's in and what's out during the Days of Unleavened Bread? For the more myopic COGophiles Jewish understanding of the Tanakh doesn't really matter, only what their own authorities have decreed. John Carmack of COGWA, for example, can pontificate: "It should be noted, however, that modern-day Jews keep "Passover" as a seven-day celebration, mixing the two celebrations of Passover and the Days/Feast of Unleavened Bread together. However, the Bible makes it clear that they are two separate celebrations." Don't worry about all those rabbis and Talmudic scholars down the centuries, it's our own less-than-a-century-old tradition of fundamentalist dilettantes, founded by a failed ad salesman with alcohol issues, that has the inside track. Oh yeah, that's credible.
When it comes to advice on what can and can't be consumed over the period of unleavened bread, the Jewish approach is varied, as demonstrated in this article from Atlas Obscura (thanks for the link, Bill! I still mourn the passing of your website.) Kareth, chametz, kitniyot... I don't know about you, but I've been pushed up the learning curve. Nothing is, it seems, as simple as it first appears.
There's a bigger issue here, though: what species of arrogance does it take for an ostensibly Christian group to appropriate Jewish traditions, modify them, impose new meanings to fit in with their literalist eschatology, and then imply that they can teach someone else's granny how to suck eggs?
It gets even worse when we're dealing with the Feast of Tabernacles, but in the spirit of Leviticus 23:4 - declaring the holy days in their seasons - let's leave that till later in the year.
For those folk who are observing the COG version of DUB, I hope everything goes well. But do keep an open mind, and do remember that your pastor and his bosses are winging it when it comes to the details.