I've organised three funerals in my time. For all three, we did have 'family flowers only' but said that people could make a gift to the charity collection at the crematorium instead.
When people first started doing this in Scotland, the understanding was that the money that you would have paid for flowers went to the charity collection: I used to put in the £20 that I would have paid for the flowers. (It's more nowadays, of course.)
When my parents died, I was surprised to find coppers in the collection and finished up adding to the collection myself to make a decent amount for the charity.
If I attend a funeral at a cemetery and there's no 'Family flowers only' notice, then I do buy a wreath or spray.
I did get cards when my husband died 5 years ago, during lockdown. The one that surprised me was the card that arrived from my husband's adult children: they lived in two separate households, but one blank card with a view of the area where one household lived had been signed by a member of each household. This was the same card that they'd sent for birthdays etc previously.
I'd rather that they'd not bothered at all. (They had decided that it wasn't safe for them to travel from England for the funeral, so that's possibly why they sent a card.)
I do recall that they did something similar one time when I had a birthday - one card came from the two households. I recall my husband looking at it and saying "What's wrong - could they not afford another stamp?"
I think that customs are changing nowadays and that explains a lot. The traditional sympathy cards that I got came from older people and I recall that I got flowers and cards from Moonpig type firms from my husband's nephews and younger former colleagues who have kept in touch. (I'm retired.)
I'll add that there was a month between the death and the funeral, so people had much longer to organise something. I suspect that in your case, @OP the shorter time period which is more common in Ireland might have had an impact.
Also, as others have said, people are definitely sending fewer cards these days.