I was looking to use this regulator to step up and regulate a lipo battery to 5 V to power my loads. I was just wondering if there would be an issue if I connect a 5 V USB-C power source to the Output of the regulator (not the input). Do I have to worry about possible damage to the regulator or battery at the input due to this?? Is there any safety measures I should take in my design before implementing this?
It is generally not good practice to directly connect the outputs of two power supplies together. They might fight each other and one or both could be damaged. This thread about connecting the outputs of two regulators has more discussion about it.
You could connect them if you add some kind of protection to make sure that power will not flow back into either supply’s output. Protections like that could be as simple as diodes (which are not very efficient) to something like our power multiplexers; the TPS2113A Power Multiplexer Carrier or the FPF1320 Power Multiplexer Carrier.