Picking avocados.

I gave up, too much faffing, I buy the smashed avocado pot in aldi, I can just open it and use it whenever I need it and it's always pretty good.

Mightn't be the answer you're looking for, but it works best for me.

https://www.aldi.ie/product/specially-selected-classic-smashed-avocado-000000000404749001

You’ve touched on it a bit in your post but the trick with avocados is to place your thumb and index finger over the more narrow end and gently press (don’t maul the things). If there is a slight bit of “give” that’s indicative the avocado is ripe or nearly there.

Another is to press against the woody stalk at the top of the fruit - if that falls away or is easily moved with little force the avocado is ripe

Look for Hass avocados with knobbly skin. There are other varieties that tend to be a bit more watery and not so creamy. I prefer the larger ones rather than the net of small ones. Don't worry if they are rock hard unless you want to use one immediately.

To ripen a hard avocado just leave it out on the counter. It can take 4-5 days to soften if it is very hard but it will soften. Once it's ripe you can leave it back in the fridge which will slow down any further ripening.

If you use a part of an avocado, leave the stone in the remaining part and wrap a bit of cling film around it and it should be ok for a few more days. Even if a part of the inside looks brown there is usually some nice fruit left once you cut away the discoloured part.

I’ve discovered that leaving them in direct sunlight speeds up the ripening, as a fridge slows it down. Using both means I can have avocados almost every day.