You will not find a company that will waive or ignore pre-existing conditions. It is an inherent part of their assessment of the risk of insuring someone.
Depending on the nature and extent of the condiitons, companies will charge more to insure you. Or decide not to insure you at all - which is what happened to me when our annual policy came up for renewal. I know from a discussion on another forum that it is an increasing issue of companies declining to insure folk.
So, it becomes a matter of finding a more specialist company that is prepared to take you on. The Money Saving Expert has a good article on the whole subject - https://www.rcnguide.com/insurance/travel-insurance-for-pre-existing/
We were able to get covered by Staysure. They offered a 15 month policy taking into account all our various conditions and including cruise cover (we have one booked for next year). Cost for the two of us was just under £1000.