You can get rebuildable pod form factor devices (or rdta pods for some).
I'd never even entertain the idea of a prefilled pod, that's just silly imo.
External batteries are good, and also unwarranted - depending on the situation. On the spryte, I find one charge lasts exactly one fill, which lasts about one work day or pretty much a day out - but the device is small enough to carry another instead of cells and bottles. On the odo, a charge lasts about a pod and a half, but carrying a spare pod is hardly challenging.
Integrated cells failing is something I used to have a concern about, but really isn't an issue with most devices. I have one spryte that's over a year old, and another a few weeks old - the older one has lost maybe 5% of it's capacity in that time, judging by the juice dregs left when the battery light flashes - and it's been dunked in a cup of tea, used in sub zero temps, left in the sun, covered in mud and rained on...
High power in a pod is contrary to how I use them and how I consider they're intended to be used, but many will do 40w, some will do 70-80w with an 18650. Pointless if you ask me, but hey.
Thing is, they do a decent job of doing what they do. If you want more then imo use a mod. If you want high power, use a mod. If you want epic cloudage, use a mod. If you want a single charge to last a week, use a nokia 6210 with extended battery and give up vaping
They're not a do everything device to me, they just are what they are and if that fits one aspect of your vaping requirements they're unmatchable.
If I think I'm going to be out/away for more than a day then I'll take my legend, or a pair of picos, with spare batteries, juice and fitted with an rta or two. But if I'm going into town, or going to work, or taking the kids out - it's a pod or two that goes in my pocket.