38 or 39 of the CGs have h-content. There are 59 total CGs in Maid Mansion. Some other CGs have mild content, not full-blown h-scenes. Each of the six main cast has at least 4 CGs, sometimes 5. There are endings with 8 of the characters, 6 of the mains cast (in logo) and 2 of the backer ladies. The 3 other backer maids have 1 h-scene CG each.
The game is DRM-free on all platforms. The only thing you could potentially miss out on by getting the game on Steam instead of itch.io is the version for Android devices.
Regardless, if you want to support the game and the developer the most, then buy the game on Steam and write a positive review. It helps us reach more customers on the most popular platform for gaming.