These are all interesting questions, and I have no idea of the answer.
Annual ticket renewed in April, so I've never had occasion to use my current ticket (indeed, I believe the recommendation is still that public transport should be used for essential travel only, and as I can work from home, any transport would be non-essential).
Ar present I'm working from home till the end of the year, and that's likely to be extended unless the Coronavirus situation changes radically. Furthermore, with new work practices it seems unlikely I'll be commuting every day after the end of the pandemic, and it may be that a season ticket will no longer offer the best value.
If I cancel my unused ticket now, would I get a full refund for the year?