What Steam Replay covers
Steam Replay summarises your year on Steam: the games you played, roughly when you played them, how your time distributed across months, and which titles dominated. It is generated from Steam's own records, and it is genuinely well done.
It also, necessarily, ends at the edge of Steam. Games from the Epic Games Store, Game Pass, GOG, EA, Ubisoft, Battle.net, and itch.io are absent, as is everything you run from a folder. For a lot of people that is most of their year.
Why a complete year in review does not exist
No store can build one, because no store sees the others. There is no API that exposes a complete, retroactive playtime history across launchers, and even where partial data exists the definitions differ. A complete retrospective has to be built from your own measurements, which means the measuring has to start before the year does.
Build your own, starting now
PlayCounter records every recognised game you play on Windows, from every source, with dated session history. Leave it running and by the end of the year you have the underlying data for a complete retrospective: total time, per-game totals, session counts, and the distribution across days and months.
Unlike a store summary, it includes the free game you got from Epic, the Game Pass title you played for a weekend, the twenty-year-old GOG game, and the itch.io jam entry. And unlike a store summary, it is built from data on your own machine.
The catch is the obvious one: it can only summarise what it observed. Install it in December and December is what you get. The earlier in the year you start, the more complete the picture.
Keep Steam Replay too
These are not in competition. Steam Replay remains the better archive of your Steam history because Valve has years of it. A local tracker is the way to make sure next year's retrospective includes everything else. Use both.