Workaround to load BP Templates into WP FSE

bp-custom.php

<?php

function g_buddypress_template( $template ) {
	if ( ! function_exists( 'gutenberg_dir_path' ) ) {
		return $template;
	}

	return gutenberg_dir_path() . 'lib/template-canvas.php';
}
add_filter( 'bp_buddypress_template', 'g_buddypress_template', 10, 1 );

function g_buddypress_render_post_content( $attributes, $content = '', $block ) {
	if ( ! in_the_loop() ) {
		the_post();
	}

	$wrapper_attributes = get_block_wrapper_attributes( array( 'class' => 'entry-content' ) );

	/** This filter is documented in wp-includes/post-template.php */
	$content = apply_filters( 'the_content', str_replace( ']]>', ']]&gt;', $content ) );

	return (
		'<div ' . $wrapper_attributes . '>' .
			$content .
		'</div>'
	);
}

function g_buddypress_override_post_content_renderer( $settings = array(), $metadata = array() ) {
	if ( 'core/post-content' === $metadata['name'] && is_buddypress() ) {
		$settings['render_callback'] = 'g_buddypress_render_post_content';
	}

	return $settings;
}
add_filter( 'block_type_metadata_settings', 'g_buddypress_override_post_content_renderer', 10, 2 );