No experience of this myself, but thinking about me dad who was diagnosed with heart failure. He’s back out doing 30-40miles on the road. It’s been a long gentle process.
Speak to the docco and keep posting here.
There’s a good bunch of people here who will support you.
How about using the bike to bimble the shops to start with then build from there.
Take care of you and keep talking it’s clearly going to be a change for a bit.