It is more complicated to suggest something natural if thyroid is fully removed then is not - but many people whose thyroid is completely surgically removed - have still very small peace of it left, that can be seen through scanning. Anyhow, if one cell of thyroid tissue is left, this cell can replicate, so healing with natural remedies is very possible and can be successful. Body has it´s own systems to establish balance after removal of thyroid - I know woman who for years after removal of thyroid did not need to take any hormone at all and felt great, but after her perimenopause started - verious health problems started to occur.
Thyroid hormones are interconnected with sexual hormones, with hormones of pituitary gland, etc.So overal hormonal balance need to be established.
There is no one remedy that should be taken in such cases, several of them are needed, but which ones can help can be recommended only individualy, because everyone needs something else. There is no universal remedy that would "fit all" people without thyroid.
Homeopathy knows many remedies that gently activate natural production of hormones that are missing: it has solutions for thyroid as well, but only if treatmant is done like I described above - to establish full hormonal balance and at the same time heal all health problems somebody has (problems with immunity etc.)