I'm also not really sure why one would pick 24V for most applications. 12V makes sense for RVs, boats, etc. because a lot of devices are designed to operate directly off 12V. 48V makes sense for houses and solar installations, if for no other reason than smaller-gauge wires (and is a big reason I'm considering it; 00 gauge wires are enormous and unwieldy). But 24V? You're likely not running much natively off 24V, so you're already going to be doing DC-DC conversion down to 12V. And there's not much cost difference between 24V and 48V inverter systems (and in fact many of them can already handle both voltages).

My first phase DC system, currently in my RV, is a single 12V lead-acid battery, single 100W solar panel, 12VDC->120VAC inverter, a few buck converters for 5V electronics and USB ports, and a bunch of stuff running off 12V (my cell modem/router and my Beelink mini-PC are 12V direct). 12V adapter for Starlink PoE. I'm waffling on getting one or two 280Ah 12V batteries to wire in parallel, or just sticking with my crappy 12V lead-acid battery for the rest of this year and getting multiple 48V LiFePO4 when I do the full solar build-out next year.

You're not supposed to mix-and-match battery brands, manufacturing dates, time in use, etc. because if there's too much of a mismatch, they'll all degrade faster (so I've read). This is what's preventing me from incrementally building up a 12V battery bank by adding another 280Ah every few months. Instead I'm planning to milk what I have as long as possible, pick a voltage, and buy a whole bank of batteries and solar panels all at once.