"SVG fonts" as a data file that uses SVG markup to define a font resource has been deprecated; it turned out to be a bad idea, and ended up not addressing the issues that typography on the web needed addressing. It was added in SVG 1.1 but removed again in SVG 2.0, and almost all browsers that did end up adding support for it removed that support again since.
Instead, all browsers now support "webfonts": regular OpenType fonts packed for the web using the "Web Open Font Format", aka WOFF/WOFF2, based on the OpenType format, which supports several different outline types:
- TrueType (quadratic curves and compound glyphs, often with
ttf
extension, but the extension is literally irrelevant)
- Type2 in CFF/CFF2 (cubic curves and arbitrary subroutines, often with
otf
extension, but again: the extension is wholly irrelevant)
- Embedded bitmaps (yes, OpenType fonts can indeed be true bitmap fonts, with as many different bitmaps as necessary to cover as many pixel sizes as necessary)
- SVG (that might be surprising, but SVG is the exact same kind of vector graphics language as TT and CFF/CFF2 are, so it made sense to allow glyph outline data to be specified using SVG as well, particularly for fonts that need explicit colour palettes, like emoji fonts)
So if you absolutely need to keep your SVG data around, then make yourself an OpenType-with-SVG-outlines font, and then pack that for the web as a modern WOFF2 (or older WOFF) and you're good to go. There are plenty of online tools to do that for you, but you can also just use something like the open source FontForge application if you want a font that only includes what you need, instead of what online tools foist into them.