Techincally this is feasible

I did a test project early for something similar when i played with Ninox early on

Not sure if this is any good to you as a starting point but ...... as I don't have the app now however I do hav something silmilar hich goes long the lines of ...

 

Create master table (table1) and on that table form a have a view to the table that you want (table2)

on the view - show the fields (and in particilar the one field you want to search on)

above that view have a text input box (or this could be a choice filed with A-B C etc) and a button 

in the box you type J - Press the button and it searchs the field in the view (eg jobdescription in image below) for all names (jobs) beginning with J

the button will have the script to to grab x number of charcters in the search string...

You don't have to have the button!!! you can put the script directly into the forumla of the view table

 

in my example below

any text entered into either the Search Item AND/OR Search Ref box

auto filters the list below to that match in either of 2 fields (Job Description and/or Order Ref

the script is in the Formula of the table view property so it AUTO searches

script

let myID := Custid;
let myItem := 'Search Item';
let myRef := 'Search Ref';
select JobDockets where Cust_ID_fx = myID and Desc like myItem and 'Order Ref' like myRef

 

You should be able to mod this to extract the first x characters only

also see the text Functions heading in this link

https://ninox.com/en/manual/calculations/reference-of-functions-and-language

 

Mel