Delaware has no general sales tax
Delaware does not levy a general state sales tax. There is no dollar threshold, no transaction count, and no economic nexus test to cross, because there is no sales tax for a remote seller to collect.
StateWise does not monitor Delaware. It is one of four states in that position, alongside the other three listed in the jurisdiction table.
What this does not mean
Sales into Delaware are still shown in StateWise under "total into this state", because that figure is every dollar shipped to a state regardless of what the state measures. What Delaware has no version of is the second figure, "counts toward the threshold", since there is no threshold for it to count toward.
Other taxes a state can levy are outside what this tool looks at. StateWise monitors economic nexus for general sales tax and nothing else, and a state with no sales tax can still have obligations of other kinds that this page says nothing about.
Sources
The four no-sales-tax states are recorded in StateWise's own jurisdiction table, which is published in full with per-row sources at the jurisdiction table.
Related: how StateWise counts your sales and what StateWise reads, and what it ignores.