I'm solo in a European capital, with my DH and DD in another EU capital.
I just got a 2nd key and plan to have that in my office (open very long hours daily except Sunday) so someone can get it to get to me if needed. And I can easily get it for visitors.
I've had to build a small toolkit - Lidl tools are perfect, and I have an IKEA rechargeable powered screwdriver and different bits for that, some duct tape, superglue etc.
I have a camping solar panel to recharge a powerbank - but am considering a proper solar generator as I have a very sunny living room and it's an all-electric apartment. If I do, I plan to get a single ring induction plate as an alternative means of cooking as open flames are not allowed so my camping gas stove can't be used. (My current alternative plan is a chafing dish with a few rather than just 1 tealight - as I don't think there are specific rules about candles).
I have a small but covers most emergencies first aid kit and meds for diarrhoea, upset tum, cough and cold, pain meds etc. I am also taking vitamins and supplements to make sure I am healthy generally, and making a big effort to eat plenty of fresh fruit and veg and not too many processed foods. Like keeping up my yoghurt and berries for breakfast habit (but now in a bowl and without seeds and oats as I don't have a smoothie maker anymore) and getting back to an old habit of lemon juice and honey with warm water in the mornings before food.
I worked to rebuild my pantry fairly quickly when I arrived - having a few packet soups, pastaria type all in 1 mixes for pasta'n'sauce/risotto etc, and part baked bread on hand. And plenty of basics and a variety of spices/seasonings to pull together meals if life has got too hectic and I haven't made it to the shops (much more restricted opening times than I'm used to) or if I come down with something. And bottled water too - 2 bottles of still for emergencies but I go through a lot of sparkling on an ongoing basis.
I've also worked to get sensible meats in the freezer and do some batch cooking to have sauces made up to defrost and reheat midweek (I don't have a microwave for ready meals).
I don't have a car, but I know the public transport routes fairly well and I have printed out the options locally in case the metro goes off for alternatives. I have a public transport card to make it easier. I have a bike as well but the weather has been rubbish and I've been too busy to get out on it yet and I am close enough to walk or use metro everywhere.
I got a "granny trolley" for my shopping - everyone uses them here and it does make it easier. I am able to get my heavy 6pack of 2l sparkling water as part of my weekly shopping easily. Or get a couple of bags of compost from the local hardware store.
I have a few things growing on my balcony - salad leaves, herbs, peas, tomato etc. I'll add more as the weather is heating up. Partly as an interest, partly to have good quality veg to eat and partly as cost of living is high especially veggies which are both more expensive and far lower quality than at home.
I'm working on improving my fitness as I would need to rely on myself if something happened.
But I know I need to build things like a bug-out bag (there are various threats here at times) or hospital bag, and fill a few gaps in my first aid kit. And figure out how to keep the apartment cool in summer (I have an air con unit, and some door stops for keeping doors open when windows are open for airflow (not when aircon is on) in cooler parts of the day, but it is a warm city in summer).