Thank you everyone, it's just good to get it off my chest occasionally. I lurk on the various Elderly Parents threads already, but haven't yet felt like posting. This thread feels more like "home"!
There isn't social care in the sense it is available (theoretically!) in the UK, but it is possible to arrange for paid carers/assistants. And when the time comes, care homes are far more affordable there. Between me and DBro, we can just about afford to pay for carers and (eventually) a care home for dad.
My parents' troubles are compounded by the state of their apartment. Before my dad became obviously ill, he was obsessed with trying to make money from various businesses. His last business attempt was some sort of second-hand reselling scheme, and he filled up the apartment with boxes of "stock." Then not long after that came COVID, lockdown, and his dementia diagnosis. So, combined with my mum's longstanding hoarding tendencies, their apartment is absolutely stuffed full of crap. Myself and DBro have been trying to get their mess under control for years, to no avail. Although the main working areas have been kept clean (bathroom, kitchen, half the dining table, living area for watching TV) the higher areas throughout are thickly coated with dust because mum can't physically reach all the boxes and stuff. When I was there last month, I tried to clean up as best I could, but it's impossible to keep control of the dust on top of all the stuff.
Now that mum could do with some help caring for dad, she's too embarrassed to allow "outsiders" into the apartment so she says she has to care for him by herself. Ditto whenever anything breaks down - if my brother can't fix it on one of his trips home, it just stays broken because mum won't call a repairman.
Mum also says that it is "too soon" to put dad into a care home because he still knows enough about what is going on around him, and will know that he has been "abandoned." I suppose she is right.