Thanks for putting this question on here, it helps when others have the same question later.
As far as multi-site goes, the best answer is yes and no. I’ll explain. Imagine that we’re renting you an unfurnished room. You then ask us if the room is compatible with the bed that you want to put in it. The answer will always be yes, but with an important side note. As your landlord we recognize that you may want to put all types of beds in the room, and we welcome you doing so. However, we do not technically offer anything specific to helping you use that particular bed, or with installation/troubleshooting of it.
This basically to say yes it is supported in that you have the freedom to install/run it, but no in that we do not offer a direct path or offer any assistance in setting it up. The analogy was probably not necessary for you, but may help others reading in the future.
As far as migrating to a containerized platform, this is a much more difficult question. I’m afraid that it has no single right answer. I went in search of some writing on the subject, and I thought that this did a really good job of asking the right questions to get you thinking about the steps: