Need advice, DC/DC stepdown, 12V in, variable out

Here's the offer. Convince me that the part number you suggest is the best at this job and very reliable, and I will buy one for me, and a free one for you.

I have a portable radio I use a lot, and it works off of 9V or a 110V AC-adapter. It uses six 1.5V disposables in series, but I know I could run it off of a DC/DC powered by lithium cells (I have a bunch). I also have a 14V solar PV panel designed to charge 12V SLA's (which are 13V when fully charged). My cell phone and favorite flashlight run off of a common 5V USB (each has its own on-board 4.2V charger), and I have several 12V-to-USB adapters (very common).

I used to live in earthquake country, and now I live in tornado country, so...I would not be shocked to have the power go out on me for several weeks at some point in my life (see: Puerto Rico, September 2017)

I also have several LED lanterns that run off of anything from 4.5V (three AA's) to 6V (four D's). My plan is to make dummy cells to insert into the stock battery cubby-hole and have two wires exiting these devices with a common socket style (XT60?), and the voltage posted on the wires. I will make up several 18650-packs with an embedded DC/DC and voltage readout. Charge lithium packs with 12V, and power several devices with adjustable DC/DC output.

My laptop is labeled 19V (actually 6S), but I have a 12V-to-laptop charger...

Results will be posted here.

I used to have something like this until I burned it out doing something stupid. Very handy. All you would need to do is put a standard automotive outlet on your supply battery and then you could plug it in and get your choice of voltages.

https://www.homedepot.com/p/CyberPower-Universal-DC-Adapter-2000mA-CPUDC1U2000/301311552?cm_mmc=Shopping%7cTHD%7cG%7c0%7cG-BASE-PLA-D27E-Electrical%7c&gclid=CjwKCAjwhOvPBRBxEiwAx2nhLslsKs4sarVF5Yt44-EbuYCbIAvEJc9ZjXRtSnCuQKlj8BgFcz8kfxoCYl8QAvD_BwE&gclsrc=aw.ds&dclid=CNOv19O7odcCFQKNfgodmRoDYw

https://www.ebay.ca/itm/DC-DC-Step-Down-Power-Supply-Adjustable-Module-With-LCD-Display-With-Case-GM/262602211968?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
I've been using this to charge my strings on my lithium batteries, as long as your input is at least 1v higher than the output it regulates quite well, check output with a voltmeter though because on mine 4.05 is 4.10 and its good for 2 amps continuous. My input is an old sony laptop charger thats 16v 3amps and it works perfect, if you substitute the sony for lithiums it would work just as well

Performance:

Input Voltage: 5~23V, Max 23V, recommended to use within 20V
Input voltage must be higher than the output voltage 1V above
Please check the input positive and negative polarity before connecting, reverse may damage the components

Output Voltage: 0~16.5V adjustable (It can save the last set voltage automatically)