I agree with Alf0nse that footbeds provide stability in any shoe, but having had custom orthotics made a few times (once for general use, once cycling specific and once after I severed a tendon in my foot!) I tend toward the opinion that the heat mouldable ones give 90% of the benefit at 10% of the price.
You stick them in the oven for 10 minutes or so, take them out and stand on them when they're soft. They mould to your foot shape, cool and stay in shape.
Could be worth trying some heat mouldable footbeds - Sole for example https://yoursole.co.uk/collections/mens-footbeds
I agree with Alf0nse that footbeds provide stability in any shoe, but having had custom orthotics made a few times (once for general use, once cycling specific and once after I severed a tendon in my foot!) I tend toward the opinion that the heat mouldable ones give 90% of the benefit at 10% of the price.