Take anycubic's approach to implement power outage support. SD card wearing can be prevented by disabling it via POWER_OUTAGE_TEST flag.

Marlin/src/sd/cardreader.cpp

@@ -34,6 +34,11 @@
 #include "../gcode/queue.h"
 #include "../module/configuration_store.h"
 
+#if defined(POWER_OUTAGE_TEST)
+extern unsigned char PowerTestFlag;
+extern char seekdataflag;
+#endif
+
 #if ENABLED(EMERGENCY_PARSER)
   #include "../feature/e_parser.h"
 #endif

Marlin/src/sd/cardreader.h

@@ -153,6 +153,7 @@ public:
   static inline int16_t get() { sdpos = file.curPosition(); return (int16_t)file.read(); }
   static inline int16_t read(void* buf, uint16_t nbyte) { return file.isOpen() ? file.read(buf, nbyte) : -1; }
   static inline int16_t write(void* buf, uint16_t nbyte) { return file.isOpen() ? file.write(buf, nbyte) : -1; }
+  static inline long GetLastSDpos() { return sdpos; };
 
   static Sd2Card& getSd2Card() { return sd2card; }