Question about flexibility with homebrewed campaigns

Hey everyone, I have had a custom world that I put a ton of work in to that my in person group has been playing in for the last two years. This has custom classes, lots of custom items and custom monsters. Unfortunately about 3 months ago I moved away from the rest of my group, and we are still interested in playing together, perhaps with Roll20 to facilitate. However what I am seeing leads me to believe that a lot of the custom content I made (currently on D&D Beyond primarily) is simply not compatible with Roll20. Is this true? There is a lot of info to sift through so a straight answer would be helpful. We may just start over and run a campaign in my world but using largely RAW and throwing out my homebrewed stuff, but that seems like such a waste if there is a way to incorporate it. Advice from other homebrew happy DM's would be extremely welcome.  -Thanks Khel  Oh and I don't mind paying for a subscription if that gives me functionality to add my homebrewed stuff, so nothing is off the table. 

You can type or copypaste whatever you like into your games (handouts, NPC sheets, forum posts), but there is no linkage between Roll20 and D&DB at any subscription level.

Custom items are pretty easy, as are custom monsters. Custom classes are doable, but wold be pretty much a manual endeavor, and some custom abilities might require a lot of work. (Hard to be more specific). As Gen Kitty says, Roll20 is pretty flexible. You can pretty much put whatever you want onto a character sheet, though automating the mechanics of it might be difficult.

Depending on the system or lack of system, you could go without the character sheet and use the bare journal. These method would allow you to use the bios as if it was a paper sheet then use the attributes and ability tab to create any automation you want. GK and Keith cover it for the most part. It all depends on the work you are willing to do or put the effort into it.

Thanks all, I'll probably start with working on moving one of my players over. As it so happens my one player who was a new class has decided to take a break from D&D, moving my herd of cats down to 6 instead of 7. But several of my players are custom archetypes. So I'll grab one of those characters and move him over, items and all. That should give me an idea of the work involved.