Yeah totally. Living through London suburban lockdowns it's been a lovely way to spend the winter evenings/afternoons haha! Not a spoiler, but you can complete non-story missions after the 'end' although if you're happy pottering about you may as well do them as you go.I'm in much the same boat, this is my first full play through, I'm trying to do as much as I can with the side quests and random encounters etc.
I've had a few legendary animals, mostly it involves getting some cover scent on and just scouting the areas, fishing is another area I've barely touched on.
I'm currently at 63% though the main story stand spend the majority of my time just roaming about, it's actually really relaxing lol.
I'm going to fire it up now, have my laptop on the side with some guides on legendary animal locations etc