Hello Clément,

if it is about the content image slider

https://prnt.sc/uIWjE0r0FXD3

you have the cursor arrows which indicates a drag. or click on prev / next

https://prnt.sc/OxOjvpq1AynP

To add buttons is custom work, basically you have to add them in the implementation of the gutenberg block and the pass the id/class of the buttons to the slider's options

https://swiperjs.com/swiper-api#navigation

Regarding the image popup it does function like that:

https://prnt.sc/zJMpcn_rqI_K

http://clapat.ro/themes/colega-wordpress/colega_portfolio/opulence/

Hello Clément,

the image carousel block is implemented in /colega-gutenberg-blocks/blocks/blocks.js 

https://prnt.sc/epaEfjxrsZx6

the outer wrapper. However the button can be anywhere. The content carousel is defined at line 1295 in /js/scripts.js and this is the link to the swiper API

https://swiperjs.com/swiper-api#navigation

Of interest are nextEl and prevEL parameters

Ok, great follow the code screenshot from my prev comment

and replace the code block

let inner_el = el( 'div', { className: 'swiper-wrapper' }, InnerBlocks.Content() );
let carousel_class = 'content-carousel';
if( props.attributes.loop == 'yes' ){

      carousel_class = 'content-looped-carousel';
}
return el( 'div', { className: 'swiper-container ' + carousel_class + ' disable-drag' }, inner_el  );

with following

let inner_el = el( 'div', { className: 'swiper-wrapper' }, InnerBlocks.Content() );

let pagination_el = el( 'div', { className: 'swiper-pagination disable-drag' }, InnerBlocks.Content() );
let carousel_class = 'content-carousel';
if( props.attributes.loop == 'yes' ){

      carousel_class = 'content-looped-carousel';
}
return el( 'div', { className: 'swiper-container ' + carousel_class + ' disable-drag' }, inner_el, pagination_el  );

This will insert the pagination div inside the slider wrapper div but after the slider

Hard refresh the page (Ctrl+F5) before testing

Excellent ! gj on this, Clément