Anyone know of resources like this but for capital markets? Things that would allow engineers new to trading equities, options, FX, bonds, and commodities to learn about different flows, market structure, common architectures, and other things that normally you learn from years of experience.

Equities and (listed) commodities are relatively easy to get a handle on but it genuinely takes months / years even at the frontline to understand how fixed income and FX works because its still almost entirely an OTC market. There is more central clearing than ever before but e.g. if I (say) buy a bond, fund it using a repo, swap my loot back some other currency, quite a lot of this could easily still be relying on humans pressing buttons and wiring money around.

To learn how and why these things are traded, however, read this book, the only (good) truly beginners guide to fixed income:

https://www.jdawiseman.com/books/pricing-money/Pricing_Money...

"Trading and exchanges" is the classic one everyone reads for listed markets, I should add.