Use temperature accessors

Marlin/src/lcd/dwin/e3v2/dwin.cpp

           case 4: // Extruder
             // window tips
             #ifdef PREVENT_COLD_EXTRUSION
-              if (thermalManager.wholeDegHotend(0) < (EXTRUDE_MINTEMP)) {
+              if (thermalManager.tooColdToExtrude(0)) {
                 HMI_flag.ETempTooLow_flag = true;
                 Popup_Window_ETempTooLow();
                 DWIN_UpdateLCD();

Marlin/src/lcd/menu/menu_filament.cpp

 }
 
 static void _change_filament_with_custom() {
-  _change_filament_with_temp(thermalManager.temp_hotend[MenuItemBase::itemIndex].target);
+  _change_filament_with_temp(thermalManager.degTargetHotend(MenuItemBase::itemIndex));
 }
 
 //

Marlin/src/lcd/menu/menu_temperature.cpp

   #if HAS_TEMP_HOTEND || HAS_HEATED_BED
     bool has_heat = false;
     #if HAS_TEMP_HOTEND
-      HOTEND_LOOP() if (thermalManager.temp_hotend[HOTEND_INDEX].target) { has_heat = true; break; }
+      HOTEND_LOOP() if (thermalManager.degTargetHotend(HOTEND_INDEX)) { has_heat = true; break; }
     #endif
   #endif
 
     //
     // Cooldown
     //
-    if (TERN0(HAS_HEATED_BED, thermalManager.temp_bed.target)) has_heat = true;
+    if (TERN0(HAS_HEATED_BED, thermalManager.degTargetBed())) has_heat = true;
     if (has_heat) ACTION_ITEM(MSG_COOLDOWN, lcd_cooldown);
   #endif
 

Marlin/src/lcd/tft/ui_1024x600.cpp

 static void moveAxis(AxisEnum axis, const int8_t direction) {
   quick_feedback();
 
-  if (axis == E_AXIS && thermalManager.temp_hotend[motionAxisState.e_selection].celsius < EXTRUDE_MINTEMP) {
+  if (axis == E_AXIS && thermalManager.tooColdToExtrude(motionAxisState.e_selection)) {
     drawMessage("Too cold");
     return;
   }

Marlin/src/lcd/tft/ui_480x320.cpp

 static void moveAxis(AxisEnum axis, const int8_t direction) {
   quick_feedback();
 
-  if (axis == E_AXIS && thermalManager.temp_hotend[motionAxisState.e_selection].celsius < EXTRUDE_MINTEMP) {
+  if (axis == E_AXIS && thermalManager.tooColdToExtrude(motionAxisState.e_selection)) {
     drawMessage("Too cold");
     return;
   }

Marlin/src/module/tool_change.cpp

 
     // Migrate the temperature to the new hotend
     #if HAS_MULTI_HOTEND
-      thermalManager.setTargetHotend(thermalManager.temp_hotend[active_extruder].target, migration_extruder);
+      thermalManager.setTargetHotend(thermalManager.degTargetHotend(active_extruder), migration_extruder);
       TERN_(AUTOTEMP, planner.autotemp_update());
       TERN_(HAS_STATUS_MESSAGE, thermalManager.set_heating_message(0));
       thermalManager.wait_for_hotend(active_extruder);