The ini loading order is in PLD (as of 7.4.0beta2):
- openat(AT_FDCWD, "/etc/php74/php-cli.ini", O_RDONLY) = -1 ENOENT (No such file or directory)
- openat(AT_FDCWD, "/etc/php74/php.ini", O_RDONLY) = 4
- openat(AT_FDCWD, "/etc/php74/conf.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_CLOEXEC|O_DIRECTORY) = 4
- openat(AT_FDCWD, "/etc/php74/conf.d/00_curl.ini", O_RDONLY) = 4
- openat(AT_FDCWD, "/etc/php74/conf.d/00_json.ini", O_RDONLY) = 4
- openat(AT_FDCWD, "/etc/php74/conf.d/00_opcache.ini", O_RDONLY) = 4
- openat(AT_FDCWD, "/etc/php74/conf.d/00_xml.ini", O_RDONLY) = 4
- openat(AT_FDCWD, "/etc/php74/conf.d/opcache.ini", O_RDONLY) = 4
- openat(AT_FDCWD, "/etc/php74/conf.d/timezone.ini", O_RDONLY) = 4
- openat(AT_FDCWD, "/etc/php74/cli.d", O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_CLOEXEC|O_DIRECTORY) = 4
- openat(AT_FDCWD, "/etc/php74/cli.d/00_readline.ini", O_RDONLY) = 4
- openat(AT_FDCWD, "/etc/php74/cli.d/php.ini", O_RDONLY) = 4

1. load php-<sapi>.ini; if exists treat as main php.ini
2. load php.ini if php-<sapi>.ini was not found
3. load conf.d/DD_*.ini to load extra extension and zend_extension lines
4. load conf.d/*.ini to load extra ini settings not involving loading extension
5. load <sapi>.d same way as conf.d

This allows minimal patch, but still allowing to have main php ini and sapi specific overrides

To test which is main php.ini:
$ php -r 'var_dump(array(get_cfg_var("cfg_file_path"),php_ini_loaded_file()));'

https://github.com/pld-linux/php/commit/762ec2e

--- php-8.0.0rc1/main/php_ini.c~	2020-10-09 18:15:48.000000000 +0300
+++ php-8.0.0rc1/main/php_ini.c	2020-10-09 18:42:20.087488856 +0300
@@ -65,6 +65,11 @@
 PHPAPI char *php_ini_scanned_path=NULL;
 PHPAPI char *php_ini_scanned_files=NULL;
 
+static int php_csort(const struct dirent **a, const struct dirent **b)
+{
+	return strcmp((*a)->d_name,(*b)->d_name);
+}
+
 /* {{{ php_ini_displayer_cb */
 static ZEND_COLD void php_ini_displayer_cb(zend_ini_entry *ini_entry, int type)
 {
@@ -661,12 +666,14 @@ int php_init_config(void)
 		zend_llist scanned_ini_list;
 		zend_llist_element *element;
 		int l, total_l = 0;
+		const char *fmt = "%s:" PHP_CONFIG_FILE_PATH "/%s.d";
 		char *bufpath, *debpath, *endpath;
 		int lenpath;
 
 		zend_llist_init(&scanned_ini_list, sizeof(char *), (llist_dtor_func_t) free_estring, 1);
 
-		bufpath = estrdup(php_ini_scanned_path);
+		bufpath = emalloc(strlen(php_ini_scanned_path) + strlen(fmt) + strlen(sapi_module.name));
+		sprintf(bufpath, fmt, php_ini_scanned_path, sapi_module.name);
 		for (debpath = bufpath ; debpath ; debpath=endpath) {
 			endpath = strchr(debpath, DEFAULT_DIR_SEPARATOR);
 			if (endpath) {
@@ -679,7 +686,7 @@ int php_init_config(void)
 			}
 			lenpath = (int)strlen(debpath);
 
-			if (lenpath > 0 && (ndir = php_scandir(debpath, &namelist, 0, php_alphasort)) > 0) {
+			if (lenpath > 0 && (ndir = php_scandir(debpath, &namelist, 0, php_csort)) > 0) {
 
 				for (i = 0; i < ndir; i++) {