You might check out [List] Devices where bootloader can be relocked, few /e/OS ROMs are built to relock; if locking the bootloader is not mentioned in https://doc.e.foundation/devices/sake/install it will not be possible.
I cannot see ahead to the possibility of upgrade Android 13 to 14, but without expert intervention (for example the magnificent /e/OS OTA Android version upgrades) most users have to upgrade via manufacturer’s stock ROM in order to collect necessary updated vendor blobs. (The situation changes for a device where the Vendor no longer makes software revisions which result in changed vendor partitions)