Hello everyone!
I’d like to build a sort of “mini computer” that connects to smartphone via Bluetooth and receives various data from the custom Appinventor App I’ve made.
Now, I’m using a Seeeduino XIAO and I’m powering it with a 1.5 V AA 2700 mAh rechargeable battery and its voltage is increased to 5V through this step up module
At the moment, these sensors/modules are attached to the board:
1x RTC Module I2C
1x VL53L0X I2C
1x HC-05
But I would really like to use this Display Touch TFT LCD Nextion
Altough that display brings some questions I haven’t been able to answer for my specific circuit:
1)Can both Display and HC-05 use the same TX and RX pins? or should I use two more I/O pins to separate them? (I’d use SoftwareSerial library)
2) Since Seeeduino has 3.3 V logic would there be problems if I attach the 5V and GND pins of the Display directly to the 5V and GND pins of the Seeeduino? Alternatively I was thinking about connecting the power pins of the display to the V0 e GND pins of the step up module (if it makes sense)
3)Is the battery currently chosen suitable for the project? To be sure can I measure current draw from the battery by connecting a multimeter in series to the + side of the battery and Vin of the regulator? I’m not really into using LiPo as I don’t want them to explode so I stick to classic batteries 
I’ve also added here a drawn schematic of the circuit, to hopefully be clear in explaining my doubts 
