Some advice about substrate?

So, I'm currently setting up a new aquarium for my two turtles. It's a 52 gallon tank and there's A LOT of DIY going on
I'm trying all I'm able to do to make it not only comfortable for my babies, but also visually appealing. Now, that the tank is almost done I'm stuck with the problem of choosing substrate correctly. The thing is - I'm not from the US, and our turtle-themed communities really differ in the ways we treat our pets. Not in a bad way, just confusing. So here's options I considered and their pros and cons with the vision of turtle owners from my country.
River pebbles:
+ can be found in the wild
(FREE)
+ turtle can't eat it
- a big no for me, don't like the appearence
Crushed coral:
+ turtles can eat it i guess??? from some sources but i'm not sure
- uncertanity on the subject from the info i found
Sand:
+ comes in a lot of colors
+ visually appealing
- can cause blockage in the guts??
- will wear off (? i don't know if it's the right word for it) the pump in the filter
Pebbles from pet store:
+ comes in many colours
+ turtle can't eat it
- since i need stones to be bigger than at least 2cm (~0,7in) it's very problematic to find right amount
- really pricey
Proppant:
+ looks cool
- i've seen this option only once, so can't be sure about safety
So, what are your thoughts? In our community the most frequent point in substrate related discussion is that turtle will eat it and it will cause a blockage, so the best option is to add a couple big stones and leave the floor empty. I really want to hear a second opinion, because it's a very serious matter for me.

River pebbles:
+ can be found in the wild

+ turtle can't eat it
- a big no for me, don't like the appearence
Crushed coral:
+ turtles can eat it i guess??? from some sources but i'm not sure
- uncertanity on the subject from the info i found
Sand:
+ comes in a lot of colors
+ visually appealing
- can cause blockage in the guts??
- will wear off (? i don't know if it's the right word for it) the pump in the filter
Pebbles from pet store:
+ comes in many colours
+ turtle can't eat it
- since i need stones to be bigger than at least 2cm (~0,7in) it's very problematic to find right amount
- really pricey
Proppant:
+ looks cool
- i've seen this option only once, so can't be sure about safety
So, what are your thoughts? In our community the most frequent point in substrate related discussion is that turtle will eat it and it will cause a blockage, so the best option is to add a couple big stones and leave the floor empty. I really want to hear a second opinion, because it's a very serious matter for me.