Introduce very simple boot status string

src/gps/GPS.cpp

@@ -505,6 +505,7 @@ bool GPS::setup()
         int msglen = 0;
         if (tx_gpio && gnssModel == GNSS_MODEL_UNKNOWN) {
             if (probeTries < GPS_PROBETRIES) {
+                bootString = "Probing GPS...";
                 gnssModel = probe(serialSpeeds[speedSelect]);
                 if (gnssModel == GNSS_MODEL_UNKNOWN) {
                     if (currentStep == 0 && ++speedSelect == array_count(serialSpeeds)) {

src/graphics/draw/UIRenderer.cpp

@@ -1149,6 +1149,9 @@ void UIRenderer::drawIconScreen(const char *upperMsg, OLEDDisplay *display, OLED
     const char *title = "meshtastic.org";
     display->drawString(x + getStringCenteredX(title), y + SCREEN_HEIGHT - FONT_HEIGHT_MEDIUM, title);
     display->setFont(FONT_SMALL);
+    if (bootString != nullptr) {
+        display->drawString(x + getStringCenteredX(bootString), y + SCREEN_HEIGHT - 2 * FONT_HEIGHT_MEDIUM, bootString);
+    }
     // Draw region in upper left
     if (upperMsg)
         display->drawString(x + 0, y + 0, upperMsg);

src/main.cpp

@@ -83,6 +83,7 @@ NRF52Bluetooth *nrf52Bluetooth = nullptr;
 #include <string>
 #endif
 
+char *bootString = nullptr; // Pointer to a string that will be drawn on the boot screen, if set (used for GPS probing status)
 #ifdef ARCH_ESP32
 #ifdef DEBUG_PARTITION_TABLE
 #include "esp_partition.h"

src/main.h

@@ -101,3 +101,5 @@ void scannerToSensorsMap(const std::unique_ptr<ScanI2CTwoWire> &i2cScanner, Scan
 
 // We default to 4MHz SPI, SPI mode 0
 extern SPISettings spiSettings;
+
+extern char *bootString;