Sure, for that use case you really can’t do better than one of the existing small field or voice recorders on the market, or your phone potentially.
I was thinking about getting another super pocketable recorder for this kind of thing and was considering the Sony A10 which would be near the top of the list I guess. There’s a few other similar options out there from OM System or Tascam, but I don’t know if they would be any better.
How long does it take to boot?
from powered off to turning it on you mean?
Since it only takes one AA battery and lasts for several hours, when it’s on I usually just leave it on until I’m done and then pull the battery so I don’t usually think about time from boot to record, but I can find out if you want.
Yeah unless there’s a standby mode that’s relatively low power?
I don’t think it’s standby per-say but it lasts for a ridiculous amount of time on a single AA battery. I don’t know how they did it frankly.
I’m going to use the stereo recorder app on my iPhone, and do a comparison with the Roland R-07, which I own, but which goes through batteries so ridiculously fast I never use it.
Maybe the iPhones with stereo mics are good enough?
It took exactly 20 seconds from me initiating power on to the ready to record state.
I timed it with the stopwatch in my clock app.
I think my Mac starts up faster than that! 
It may!
but I think the h1 lasts longer on a single AA than your mac does on a charge!
" Battery life when using an alkaline battery is up to 10 hours , even during continuous recording."
As @protrusion mentions you should be able to ‘set and forget’ to a large extent. I use a Zoom H5 - all the controls I use are on the front of the device - turning on/off the mics and/or the 1/4 connections and the volume dials. For recording on the 1/4" I don’t touch anything, I might tweak the gain for recording with the mics depending on how sensitive I need it.
I turn it on and hit record.
There were only a handful of settings for me to consider when I first set it up.
For comparison’s sake: My H1n takes just under 7 seconds to start up ready-to-record.
(Using a 16 GB SanDisk Class 10 card - IIRC card size mattered for start-up times on my old H4 as well as on my H6.)
Anyone who has it, how is the H1n (quality wise) for:
Vocal recordings?
Line in recording from let’s say @48 khz elektron digi boxes?
Koala sampler + a stereo microphone ?
Having said that my Tascam DR-something has a dedicated record button so it is just 2 press of a button from a cold start, definitely not faster than launching an app on a smartphone then recording.
I have the H1n and have used it to record Digi boxes and modular (just about everything I have posted in Current Sounds here). I don’t have any complaints about audio quality. The interface can be a little fiddly (tiny screen, knobs, and switches). It is very small and light, and takes only 3.5mm TRS plugs. You have to be careful about using it, as a cable bend can move it, and then you might get some crackling from the connections. But it’s pretty handy, especially as a USB audio interface. I’ve only done a couple of vocal recordings and I wasn’t that concerned about quality, so I can’t speak to that aspect.
pretty easy to buy at Reverb or Ebay. also, the D100 can be had new
then why even consider ‘saving for the TE’?
sony pcm d100 is pretty much the best bet. and no weakness to speak of
This app can record in stereo and you can select, which iPhone mic you want to use: https://twistedwave.com/