bathoutdoors.co.uk is a huge fan of drj0n bagworks & his perfectly engineered solutions for bikepacking adventures. The drj0n bagworks Barnacle allows you to secure/bolt a multitude of things to suspension forks, various frame tubes, seat posts.
A couple of considerations, you may wish to use some tape or a rubber shim to provide a bit of additional friction or frame protection. Be aware of the bolt length you're securing to the barnacle, too long and you'll damage the device.
Photos for functional reference only, please ensure you measure diameter to match the correct product.