The LNA from Pipelie uses an AZ OP (or 2) and thus has essentially no 1/f noise, at least with a short. With a actual voltage there would be noise from the coupling cap if an electrolytic cap is used. I am not sure if the noise show for the battery is more from the battery or possibly from the coupling cap.
The downside of the usual AZ OPs is the limited bandwidth, especially if the first stage is used with a high gain. So 0.1 Hz to 100 kHz could become tricky. However 0.1 Hz to some 10 KHz may be realistic for such a setup without an intentional filter for the upper limit.
Similar one may be able to extend the lower limit a little below 0.1 Hz with a larger capacitor - however things are limited there. It is not just the cross over frequency, but also current noise (which gets visible as 1/f noise with a very larger resistance instead of a larger cap) and also dielectric absorption, so that electrolytic caps need really long settling before using it for slow processes.
For measuring down to really low frequencies the way to go would be using 2 reference and measuring the difference with a DC coupled amplifier, at least for the initial stage, possibly all the way with a DC compensation.