I’m building a simple data logger
You should find plenty of threads about this on here - which ones are relevant will depend heavily on your definition of "simple".
SparkFun MAX31855 breakout (1568-13266-ND) ... I need help wiring the SPI connections between these devices and power supply decoupling—especially which devices can share SPI lines and what pull-up resistors or caps I may need
This would be a good first device, as it should have all required resistors and caps, plus examples from Sparkfun
There are also good libraries with examples for SD cards Sd_fat is my go to.
This is good advice - note that a slightly adapted SdFat is built into Teensyduino, so installing it separately is unnecessary and tends to lead to issues. Given you're using a Teensy 4.1, if you can use its built-in SD card slot everything is pretty simple (relatively speaking) ... just plug in a formatted card and try an example.
I would appreciate coding as well but I was planning to use AI to generate that.
My personal advice would be to avoid AI for coding. Obviously we only get questions on the forum when it's all gone horribly wrong, so for all I know it works really well most of the time, but I have my doubts. Bear in mind, if a large language model generates slightly awkward syntax in your English homework, you (should) notice it, correct it, and move on. When it stuffs up your code, and you have only a passing acquaintance with how C++ works, you're almost certainly stuck.
The best approach is to put in a bit of work to find a few examples that do something close to what you want, figure out enough about how they function, and combine them. It's a technique I still use after about 50 years of coding experience...
