I only plan to use my power supply (5V/3A) for powering the Pi4.
And then I have a Lemus Powerbox with 3x 12V DC ports and a 230V EU power socket for the electronic automatic focuser, dew heater and the powered USB Hub.
And I have a jump starter with 1x 12V car cigarette lighter socket (will be used for camera cooling)
Your Li 12V power bank looks very nice thou pricey. I use a classical 7Ah lead Celestron Power Bank at €70 from Amazon.de, very reliable and plenty of energy.
Per getting the time (and position) from your CEM-25P: Yes, this definitely works, and is how I run my RPi4/SM 1.5.2/CEM-25P. It's in KStars | Settings | Configure KStars | INDI | Mount updates KStars if memory serves.
Yes, I also find it pretty pricey but I like that it has 3x 12V output and with the 230V output it is also useful when I go camping with my family.
I believe that the specs of mine are similar to this one from Bresser: www.astroshop.eu/battery-packs/bresser-m...ion-100-watt/p,63756