Hi, d.f.hall, and welcome to the forum!
Scotland is one of the easiest countries to do solo as it's very friendly, scenic and people there are very helpful. I spent 3 weeks last year on a solo trip to Scotland and had an incredible time. I rented a car for most of the time I was there, as I traveled to some of the islands and wanted the flexibility. I did not find it that difficult but it does add a layer of stress if you have not driven in Scotland or on the left side of the road before.
It would help to know how long your trip is. That makes a difference with what you will be able to visit. Edinburgh and Glasgow are both must-sees, in my opinion, and you could easily do a few day trips from there on your own, like to visit St. Andrews or Stirling (with Stirling Castle).
One option would be to base yourself in a city like Edinburgh and take some tours out from there in conjunction with solo travel. For example, Rabbies Tours have a number of 1 to 20 day tours they offer from Edinburgh or Glasgow. They come highly recommended here. https://www.rabbies.com/en
Were you planning to visit the Highlands or some of the islands? Some are easy to get to and around using public transportation, such as the Isle of Arran, which has excellent public transport. Skye is a bit more difficult but you can always make your way there by public transport, then use a day tour to get around the island. They also have buses but you would waste a lot of time waiting for them. You could also head to Inverness and take some trips from there either by bus or using a tour (Rabbies also has tours out of Inverness).
One last thing I forgot to mention. It is getting harder to find accommodations in Scotland, due to high licensing taxes and a number of reasons, so you really need to book your B&B or hotel as early as possible. Now would be a good time to start. Edinburgh and Glasgow and the large places should be okay, but if you are planning to stay on any of the islands, definitely start figuring our your logistics as soon as possible.