Yes @DarthDavester, you have understood everything in my mind.
A backup always makes sense. Even before a /e/ OS OTA update. A few weeks ago an OTA update for the S5 (klte) was faulty. I thought “it will work fine” and did not make a backup. Well, it did not go well …
I just repeated my experiment on a freshly installed S5 (klte) /e/ OS e-0.11-pie including microG Services Core version 0.2.10.19420-77. Note: My device is not rooted.
This time I didn’t install the complete NanoDroid suite, but only NanoDroid-microG-22.9.20200910 via TWRP. The installation ran without failures. Now microG Services Core version 0.2…12.203315 is working in /e/ OS.
The installation of the (UK) NHS Covid-19 app version 3.6 (68).68 was just as fast and without complications.
Stay healthy & safe