Is there ANY way to get ALL fruits (apples, oranges, pears, cherries, peaches, coconuts) and flower types (roses, tulips, hyacinths, cosmos, pansies, windflowers, lilies, etc.) OTHER than through online trading?

I have yet to find a way... I have 3 fruit types (apples, peaches, coconuts) and 4 flower types (hyacinths, lilies, tulips, and wind flowers).

If not, I feel a certain way about Nintendo right about now...

I am assuming your extra flowers and coconuts came from Nook Miles trips, correct?
And your other fruit was in a letter from "Mom"?

I am in a Peach town, and received a Pear in the mail from Mom.  I'll keep an eye on my Nook Miles trips for other fruits, and let you know.

You can probably receive fruits from random letters and perhaps villagers... but I would expect that to take a looooong while.

As far as I know you can only find 1 different fruit and flower from nook miles trips. So far ive only found apples and hyacinths while im a peach/cosmo town

You are correct. Unfortunately my rare fruit island (peaches) was the same fruit I received from Mom... *Sigh*

I'll keep an eye out too for random letters but so far it feels pretty discouraging.

You can but it may take a while. I live in a pear town, got a peach from Mom, and it took me maybe 6 island trips to get an island full of orange trees. But after your main fruit, mom fruit, and the coconut freebie you only need to find 3 fruits.
As for flowers they sell some alternatives in Nook's Cranny, at least sometimes. One day I had tulips, hyacinths and cosmos for sale but for the past 2-3 days its been windflowers, lillies and pansies. Also islands will have roses, as well as all the others at random chance. I do not know what the statistics would be on finding these things though, but considering it seems they've made things a bit easier in this game I doubt you have to wait long to find them all.

I'm struggling with this as well.

Oranges are my native fruit, and I've managed to get pears and coconuts from the Nook Miles, and cherries from mum. I'm hoping to get some other fruit and flowers in the mail.

I only have hyacinths, pansies (from an island) and windflowers. I'd love to get tulips, but I'm not online so I'll just have to wait to see if it happens randomly.

I'm hoping Nintendo will change this, and make more random stuff appear on mystery islands. Obviously they want players to visit each other to get these items, but not everyone can/wants to do that.

Thanks for the responses!

So far, I've been to probably over 25 island tours with no luck.
However, it gives me hope knowing that some people have had better luck than me with islands, so it may be possible to get them without having to get an online subscription.

I get the push for a subscription-model online network since consoles have already been shifted that way now for years now and Nintendo is following suit. Though that's what I liked about DS games that you could just connect via WiFi and enjoy the game however you want to (alone or with friends).

If you're really adamant about not paying for online, if you haven't done so already you can get a 7-day free trial, so you would just need to: get the free trial -> cancel payment -> use online to get all the flowers/fruits needed before the trial ends.

Oh dang! I didn't know that. Thanks for the info, I'll check it out and hopefully set up some trades.