Right now we have an ETL that extracts info from an API, transforms, and Store in one big table in our OLTP database we want to migrate this table to some OLAP solution. This table is only read to do some calculations that we store on our OLTP database.
Which service fits the most here?
We are currently evaluating Redshift but never used the service before. Also, we thought of some snowflake schema(some kind of fact table with dimensions) in an RDS because is intended to store 10GB to 100GB but don't know how much this approach can scale.
Which service fits the most here?
imho you could do a PoC to see which service is more feasible for you. It really depends on how much data you have, what queries and what load you plan to execute.
AWS Redshift is intended for OLAP on top of peta- or exa-bytes scale handling heavy parallel workload. RS can as well aggregate data from other data sources (jdbc, s3,..). However RS is not OLTP, it requires more static server overhead and extra skills for managing the deployment.
So without more numbers and use cases one cannot advice anything. Cloud is great that you can try and see what fits you.