IFixit tried to switch parts before the usual disassembly report, and obviously you can use some iPhone 8 parts in SE without problems, cameras and screen assembly including microphone, proximity sensor, SIM tray and taptic drive will work in the newer model, on
Less as long as you don’t mind losing True Tone color adjustments, however.
You can’t replace Touch ID button from another iPhone, Apple and approved repair shops have to do this, you’ll also have to forget to replace the battery, while the lithium ion packs look very similar, SE uses a new conductor, and it won’t be an option
Available even if you can get around a warning that isn’t an original Apple battery.
IFixit still sees the second generation SE as an improvement, and the repair shop said that many new iPhones have no compatibility at all with older models.
This might work if you intend to keep your phone working for as long as possible and do not mind unlocking it, if nothing else, it may lead to faster and more affordable technical repairs if you are not comfortable with repairing the iPhone yourself.