Content gap analysis usually starts by listing all queries that competitor sites rank for in the top 10 — but your site does not. Filtered for commercial relevance, this list is the closest thing to a 'shopping list' of content to write.
The temptation is to try to fill every gap. The better approach is to filter ruthlessly: which gaps map to topics where you have first-hand expertise, where you have an obvious commercial angle, and where the competition's existing content is genuinely beatable? Three high-quality fills beat thirty mediocre ones.
Gaps are not just keyword gaps. There can be format gaps (your competitors have video, you do not), depth gaps (their guides are 5,000 words, yours are 800), and freshness gaps (their guides are updated annually, yours have not been touched in three years).