5Ah is standard for a phone of that size, but GSMArena’s tests show it underperforms given the capacity. Hopefully Motorola can improve it with updates? And I’m not sure how good custom ROM support is on their phones, it’s definitely an option as you say but all phones should have at least 5 years of security patches imo.
Finally decent software support which is nice to see. But for the price, Sony really should have updated the old, old, telephoto and also added a discrete DAC for audio. Still good battery life but not amazing like the VI