If the motherboard is bad beyond repairs, ask your repairer to extract the storage chip (eMMC) from the bad motherboard and look for a good card reader to extract the data ( if it's iPhone or higher version android phone) he would need a good specialist with forensic skills to decrypt the data because most advanced phones encrypt their Data for security reasons.
Depending on your location it can actually be expensive. The more remote the location is the more difficult it is to pull that off actually. Take for example you are in this kind of situation, when you hit up some repairers in your locale they may not have the necessary skills to fix it. It's the reason you should have a hardcopy somewhere at all times.
Seed phrase are vulnerable when store digitally so it is wise to creat many copy of it on paper and stored in a place that water can't reach a recovery phrase Totally consist of 12 to 24 random words if I may say for me I adopted the act of splitting each words of my seed phrase and storing them in different locations that only I can remember while many person I know may prefer to store it in a dry container and kept in a place that has a good temperature.
Some people can resort to splitting but personally I don't buy the idea. You ought to have them duplicated that way your have a better chance at safety.