Convert htaccess file to nginx try_file for subfolder - .htaccess

Question

RewriteEngine On
RewriteRule ^([^\.]+)$ $1.html [NC,L]
How to convert apache .htaccess file to nginx try_file?
I have static html files in the following folder structure and accessing them with pretty URL style without .html extensions it was working with apache but when I try to convert nginx config it was throwing 404 for subfolders. I used https://winginx.com/en/htaccess site for conversion.
# nginx configuration
location / {
rewrite ^/([^\.]+)$ /$1.html break;
}
+ root-folder
+ index.html - url - www.hello.com
+ abc.html - url - www.hello.com/abc
+ .........
+ xyz.html - url - www.hello.com/xyz
+ category-folder
+ category1.html - url - www.hello.com/category-folder/category1
+ category2.html - url - www.hello.com/category-folder/category2
+ category3.html - url - www.hello.com/category-folder/category3
+ page-folder
+ page1.html - url - www.hello.com/page-folder/page1
+ page2.html - url - www.hello.com/page-folder/page2
+ page3.html - url - www.hello.com/page-folder/page3
Any help will be really apricated.

Answer 1

The try_files is a good directive for front-controller patterns of dynamic frameworks powered by PHP or other languages, where you have a single bootstrap file, e.g. /index.php, which "serves" the SEO friendly URLs:
/foo/ -> /index.php
/bar/ -> /index.php
/lorem/ipsum -> /index.php
If your files are static and you know the file structure in advance, try_files brings nothing other than the performance penalty of stat (file existence check) system calls.
E.g. applying try_files $uri $uri.html $uri/ =404; from a comment by Richard, would mean that for URI /category-folder/category1, NGINX first checks that actual file /category-folder/category1 exists first, then checks if /category-folder/category1.html exists, and in case it doesn't, check if /category-folder/category1/ directory exists.
It makes much sense to stick to rewrite and converting configuration, in this case, is pretty straightforward. It will result in 1:1 match on how it worked in Apache.
Using my "fairly sophisticated" Apache to NGINX config converter, which does detect when you need to use try_files and when not, you will get the desired rewrite (place this directly in server context, not in location):
rewrite ^/([^\.]+)$ /$1.html last;
To check this rewrite you can use this test.
As you see, the only trick there is that URIs in NGINX rewrites (and URIs specified in NGINX in general) have to start with slash, whereas in Apache they are omitted.