I used to switch to mountain biking in winter. Less speed (much less for me, I am not very good on a road bike, but boy I suck on a mountain bike π), more effort: you're warmer. π₯΅
Last winter I used a 'smart' indoor trainer. Well, two 'smart' trainers. The first one lasted 2 weeks, then they sent me another one, it lasted about 2 months or so before starting to make so much noise I couldn't use it anymore. I never managed to fix the piece of crap. Well, the pieces of crap since I have two unusable specimen.
This year I have zero motivation and haven't touched a bike in over 2 months...