Switched to the Microchip WLR089 LoRa module and this brings more features. Full list of improvements:

• ARM Cortex M0+ with 256 KB flash and 40KB RAM
• Dual band, 868 MHz and 915 MHz
• USB connectivity
• On-module u.FL antenna connector so no RF path needs to be on my PCB
• Switched to the Quectel LC86L GNSS module, capable of tracking GPS and also GLONASS
• Added an Analog Devices ADXL362 low-power accelerometer for activity tracking
• Added a software-controlled LED and a button
• Added an on-board I2C temperature sensor for monitoring safe operating range of battery
• Updating firmware is much easier through USB, using UF2 bootloader
• Arduino compatibility is possible, as there are ports for the SAM R34 chip in the WLR089 module

Some limitations that have been carried over from original prototype:

• LC86L module requires a much larger ground plane, thus GPS antenna performance may be significantly reduced
• LoRa antenna is packed very tightly in case close to many other components, thus performance at 868 MHz and 915 MHz is greatly reduced