There are two places you can find out information about what Family Tree DNA holds about a haplogroup. These are the public haplotree and their Discover project:

https://www.familytreedna.com/public/y-dna-haplotree/R;name=R-FT209276

https://discover.familytreedna.com/y-dna/R-FT209276/

I mention Family Tree DNA specifically, because they hold well over 90% of all the deep Y-DNA tests in the commercial markets, and many of the early academic samples too. For shallower tests, which don't go down to the same depth, there will be more at other companies like 23andMe, Ancestry, LivingDNA, etc.

L45 is one of the SNP mutations contained in most of these shallow tests and R-L45, the haplogroup it represents, is a family of people stretching back to a common ancestor living 2500 years ago. It is very likely that a deeper Y-DNA test than the one supplied by 23andMe would place you in a smaller branch of this family - i.e., a more recent haplogroup.

Looking at Family Tree DNA's public haplotree for R-L45, we can see a total of 308 testers, of whom 134 have stated origins, of whom 101 are from Europe and 90 are from the British Isles in particular. The remaining 11 are from Germany, Denmark and Sweden. There will be many more in other testing platforms.

Family Tree DNA knows about 96 different haplogroups within R-L45. Looking at a smaller haplogroup like R-FT209276, we have seven testers, of whom three have stated origins in Scotland (1) or Ireland (2). R-FT209276 is about 2000 years old, which is still fairly old compared to most haplogroups in R-L45. It's unlikely that there are other people in R-FT209276 on other testing platforms, since only Family Tree DNA and a few other specialised companies offering Whole Genome Sequencing tests will offer tests that cover these smaller haplogroups (and can find new ones).

This shows the difference between the shallow, chip-based tests like 23andMe, and the deep sequencing from tests like Family Tree DNA's BigY test.

In terms of working out our origins, these deep tests are vital. Knowing you are R-L45 says something about where your male-line ancestors were 2500 years ago. That says nothing about where they have travelled in the last 2500 years, so it is not very useful at picking out modern origins - like any of the cultures we think have influenced Scotland or Orkney in particular. We generally don't see R-U106 in Pictish populations: R-U106 tends to be representative of later incomers to the British Isles, and the Picts appear to be mostly from the R-DF13 haplogroup, so it is unlikely that your ancestors were Pictish, but that's about as far as we can tell.

A deeper haplogroup can tell you more about your recent ancestry (though often we are still trying to work this out, and answers are rarely clear-cut). For example, my family are from Aberdeenshire. We know that they were part of the Unetice Culture 4000 years ago, but we think that they lived in France until medieval times.

When we see R-U106 in Orkney, it is more normally associated with Viking ancestry, but there are clear instances of people coming there from medieval Ireland, and the notable Orcadian family Sinclair (unproven but likely Norman French) is part of R-U106 too. So it is not a clear-cut case to say that, because your family is from Orkney, they must either be Picts or Vikings. Other possibilities remain too, and your haplogroup of R-L45 makes these more likely. R-L45 is clearly a Germanic haplogroup, but different parts of it will have gone and become the Vikings, Anglo-Saxons, Normans and other groups that populated different parts of the British Isles.

Cheers,

Iain.