The concept of colour phase alternation, the basis of PAL, was considered by (I think) Hazeltine labs in the very early 1950s. While NTSC was being developed. Until there was a practical 1 line delay available at low cost the advantages of CPA were minimal. Both SECAM and PAL depended on having a 1 line delay in the receiver. Less critical for SECAM than PAL. Simple PAL receivers (without a delay line) were feasible but were hardly, if at all, marketed. The results were not good.
As for PAL N, I worked for MIchael Cox Electronics in the early 1980s when Argentina went to PAL N. We designed and supplied PAL B to PAL N transcoders as all production was done with standard PAL B kit. ISTR the pictures, as viewed side by side in the lab, weren't bad. On critical material you could tell the difference. Of course VHS and Betamax recorders reduced picture quality to below PAL N.