So, to be clear, is all such dating to time periods done by radiometric methods?
No, although radiometric methods are by far the most accurate and convenient.
One thing you are forgetting is that "radiometric methods" covers a plethora of different and independent techniques that are used to cross-check each other. Nobody's ever come up with any physically possible ideas on how the results of all these techniques could be changed and still agree.
Of course for times less that 50,000 years there is a score of methods, all of which agree. That agreement the most difficult thing for creationists to address, so they never try. But for significantly older ages there are some techniques.
Milankovitch cycles leave evidence behind that we can use for absolute dating. Sunquakes have changed over time as helium accumulates in the core, and that can used to calculate the ages of meteorites, and that calculation agrees with radiometric methods. Amino Acid Racemization can date items as old as two million years if they happen to have been preserved in ideal conditions (e.g. Antarctica).