[Egret]

https://pmc.ncbi.nlm.nih.gov/articles/PMC1892545/

An upper bound probability for the RNA world hypothesis is 10^-1018. A reasonable interpretation is that the RNA world hypothesis is impossible in the real world.

[avadodin]

A superficial reading doesn't inspire much confidence in this peer-reviewed article but I agree that RNA-world is a thought experiment at best. There is no evidence of these RNA structures in actual lifeforms. RNA encodes proteins. The most parsimonious explanation is that proteins(likely incapable of true replication by themselves) preceded RNA even if an RNA-based system can be designed in theory. I won't make claims of probability of unknown processes but proteins exist that can assemble spare nucleotides and proteins exist that can assemble proteins out of nucleotide chains. All you need is a pair of them to come in the vicinity of each other and wait until RNA comes along that encodes a similar-enough pair.

[Egret]

The probability of assembling two proteins randomly close by in spatial and temporal terms runs into Chadwick's proximity problem.