I only trust Coach Greg’s Lazer Eye Vision ™ to measure body fat. lol.
They are all a bit of a crap shoot. If you watch a bunch of fitness YouTubers documenting their Dexa scan results you will see a huge variance in appearance / measured body fat and also just some BF% that would see these people in graves. Dexa results can vary based on your hydration level and and glycogen depletion, just as a scale using electrical impedance does. Does my BF change by pounds day to day as my scale indicates? No, just hydration levels are changing. MRI is probably the most accurate but unless you have tons of disposable income you probably can’t afford it on a regular basis.
If you can deal with the ranting and Gilbert Godfried voice:
Probably the most simple way is to use a skin fold caliper and just track measurements at various parts of your body. Don’t use the measurements to estimate bodyfat (there are different models for different distribution of body fat, which do you use?) just track the measurements for progress.