Yes bitcoin mining can be done on mobile phones but as supposed this can't be effective or productive due to lack of processing power. Today mining is dominated by ASiCs hardware with high computational power making mining very competitive. But trust me bitcoin mining on mobile devices isn't practical today, but you can earn micro quantities from faucets or running a lightening network on some android setups which isn't mining but a small way of supporting the network. In summary don't fall for crap app that claims to be bitcoin mining apps, those are likely scams
Even powerful desktop/laptop computers are not recommended for Bitcoin mining because of huge hash rate. Those who want to mine Bitcoin have to buy expensive special devices (ASIC devices) that require round the clock connectivity and also consume too much energy. Bitcoin mining is an expensive thing these days and those with huge capital can afford it. Those who can't afford bitcoin mining must go for bitcoin buying through DCA. If someone is interested in mining on mobile phone then he must look for Alts whose mining is profitable on mobile devices.