As I began this discussion, I thought I'd inform of my decision. I bought a used Zoom R8!
I noted advice in this and parallel threads. Jim's comments convinced me to drop the Livetrak and I made a short list of the two portable Tascam models, the Zoom R12 and R20. All retail below 450€ which was my budget.
I then read manuals, reviews, user comments and watched many YT demos, how-to's and comparisons between models.
The R20 wins hands down on features per dollar but unexpectedly, the idea of portability appealled to me; the R20 is definitely a HOME studio device.
I loved the portability of the Tascams, the built-in mics but was strangely put off that, although they can use AA type batteries, they can't run from a USB Powerbank. I use one for other music gear and consider this a better solution than constantly replacing AA's.
So that left the R12. No built-in mics but flexible on power sources. It's on-board synth was not appealing but overall it met my needs.
As I dug deeper into content on the R12, constant comparisons to It's predecessor, the R8 came up and piqued my interest. The R8 has built-in mics, battery operation - I couldn't find out if it would run on a powerbank, (it's original design pre-dated powerbanks) but the specs suggested that it might work! The reviews mentioned that the R12 has slightly better preamps but I was sure I could live with this!
I monitored the used market, asking prices are 90 € to 150€. I got one in superb condition, with original packaging, for 115 €. The previous owner included a 32GB card as well. Within an hour of it's arrival, I recorded a simple blues, utilising its drum-machine and effects processor and the built-in mics (for handclaps

). I also confirmed the powerbank compatibility!
I now have a very easy-to-use, ultimately portable, 8 track with everything I need built-in. I think we're going to be very happy together!
Recommended resources:
YouTube: check out the @GazRendar channel. Many helpful videos!
Also on YT: R8 vs R12 -
https://youtu.be/x-_ItUjfHOs?si=cz4REh4joI65DkeY
Helpful written reviews:
https://www.soundonsound.com
User comments: mostly on Reddit.