Most fruit tree seeds are true to type, and most members would have propagated many from seed to get pretty close to what they wanted.
Wild species and non hybrid cultivars are pretty much in this zone.
Hybrids and improved cultivars will likely throw more variable seed offspring.
The wider the hybrid cross, the more likely to get more variable seed progeny.
F1 hybrid fruit will normally give variable F2 seedlings.
Not all hybrid varieties are actually true F1 ( AABB X aabb = AaBb hybrid )
Variety cultivars may give similar but variable seed progeny.
I had a nice white peach, maybe Okinawa, that volunteered quite a few seedlings. The fruit was pretty much identical to original, but the ripening time was different by weeks and months. One seedling is so late it can't ripen before winter.
Found seedlings of Apples on roadsides can be variable, but mostly pretty similar to the seed in the core that came out the car window.
There are also many myths about "not being true from seed".
In most cases you are going to get something pretty close to the fruit the seed it came out of, some might be real duds, but most variants will be edible.
Species and cultivated varieties might need more info beforehand, if you don't have time and space to wait for results.
Some varieties from some species have nucellar / polyembryonic seeds that are clones of the parent ie some Citrus and some Mangoes.
Where seedlings are used as grafting rootstocks, the level of seedling variation is low enough to allow fairly uniform similar rootstocks.