If you want to be really accurate, take the raw weight and then weigh it all cooked to get the exact ratio. Otherwise i usually just multiply cooked meat by 1.5x to get the approximate (i.e. 4 oz cooked is 6oz raw)
Here’s what I do. If you’re weighing all of this and tracking it, being consistent with what you do will expose this flaw over time and you will adjust accordingly. I found nutritional info for cooked versions of the meats I prep and just went with what I found. If there is a discrepancy, my consistency with tracking and weighing will eventually compensate for the error anyways. I knew I was going to have an issue with this specific area, so when I needed to adjust my caloric intake, I started by dialing back on my meats.
If I’m cooking a single meal, then yeah, I’ll go with raw, but when I’m prepping I just go with what’s been working for me all these years.
Couldn’t you weigh it raw, determine the nutritional info, then re-weigh it after it’s been cooked? Even if you just did it once you’d know the nutritional info for the cooked meat, assuming you cook it the same way each time.